RNA recognition motif (RRM) superfamily; RRM, also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), is a highly abundant domain in eukaryotes found in proteins involved in post-transcriptional gene expression processes including mRNA and rRNA processing, RNA export, and RNA stability. This domain is 90 amino acids in length and consists of a four-stranded beta-sheet packed against two alpha-helices. RRM usually interacts with ssRNA, but is also known to interact with ssDNA as well as proteins. RRM binds a variable number of nucleotides, ranging from two to eight. The active site includes three aromatic side-chains located within the conserved RNP1 and RNP2 motifs of the domain. The RRM domain is found in a variety heterogeneous nuclear ribonucleoproteins (hnRNPs), proteins implicated in regulation of alternative splicing, and protein components of small nuclear ribonucleoproteins (snRNPs).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45554213 722 EINKIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAISNP 801
Cdd:cd12392   1 EKNKLFVKGLPFSCTKEELEELFKQHGTVKDVRLVTYRNGKPKGLAYVEYENEADASQAVLKTDGTEIKDHTISVAISNP 80

                .
gi 45554213 802 P 802
Cdd:cd12392  81 P 81

K+-dependent Na+/Ca+ exchanger; [Transport and binding proteins, Cations and iron carrying compounds]

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 45554213    860 KREANGEEQKGDVQE---RDEQKGEEQKgEEQKGEEPKGEEQKGDDQIGEEQsgvEQKGDEKKEEEMPA 925
Cdd:TIGR00927  623 KVMALGDLSKGDVAEaehTGERTGEEGE-RPTEAEGENGEESGGEAEQEGET---ETKGENESEGEIPA 687

RNA recognition motif 2 (RRM2) found in squamous cell carcinoma antigen recognized by T-cells 3 (SART3) and similar proteins; This subfamily corresponds to the RRM2 of SART3, also termed Tat-interacting protein of 110 kDa (Tip110), is an RNA-binding protein expressed in the nucleus of the majority of proliferating cells, including normal cells and malignant cells, but not in normal tissues except for the testes and fetal liver. It is involved in the regulation of mRNA splicing probably via its complex formation with RNA-binding protein with a serine-rich domain (RNPS1), a pre-mRNA-splicing factor. SART3 has also been identified as a nuclear Tat-interacting protein that regulates Tat transactivation activity through direct interaction and functions as an important cellular factor for HIV-1 gene expression and viral replication. In addition, SART3 is required for U6 snRNP targeting to Cajal bodies. It binds specifically and directly to the U6 snRNA, interacts transiently with the U6 and U4/U6 snRNPs, and promotes the reassembly of U4/U6 snRNPs after splicing in vitro. SART3 contains an N-terminal half-a-tetratricopeptide repeat (HAT)-rich domain, a nuclearlocalization signal (NLS) domain, and two C-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45554213 722 EINKIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAISNP 801
Cdd:cd12392   1 EKNKLFVKGLPFSCTKEELEELFKQHGTVKDVRLVTYRNGKPKGLAYVEYENEADASQAVLKTDGTEIKDHTISVAISNP 80

                .
gi 45554213 802 P 802
Cdd:cd12392  81 P 81

RNA recognition motif;

                           10        20        30        40        50        60        70
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 45554213    725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVH-KLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:smart00360   1 TLFVGNLPPDTTEEELRELFSKFGKVESVRLVRdKETGKSKGFAFVEFESEEDAEKALEALNGKELDGRPLKV 73

polyadenylate binding protein, human types 1, 2, 3, 4 family; These eukaryotic proteins recognize the poly-A of mRNA and consists of four tandem RNA recognition domains at the N-terminus (rrm: pfam00076) followed by a PABP-specific domain (pfam00658) at the C-terminus. The protein is involved in the transport of mRNA's from the nucleus to the cytoplasm. There are four paralogs in Homo sapiens which are expressed in testis, platelets, broadly expressed and of unknown tissue range.

                          10        20        30        40        50        60        70
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 45554213   724 NKIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAIS 799
Cdd:TIGR01628 286 VNLYVKNLDDTVTDEKLRELFSECGEITSAKVMLDEKGVSRGFGFVCFSNPEEANRAVTEMHGRMLGGKPLYVALA 361

K+-dependent Na+/Ca+ exchanger; [Transport and binding proteins, Cations and iron carrying compounds]

                           10        20        30        40        50        60
                   ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 45554213    860 KREANGEEQKGDVQE---RDEQKGEEQKgEEQKGEEPKGEEQKGDDQIGEEQsgvEQKGDEKKEEEMPA 925
Cdd:TIGR00927  623 KVMALGDLSKGDVAEaehTGERTGEEGE-RPTEAEGENGEESGGEAEQEGET---ETKGENESEGEIPA 687

RNA recognition motif 2 (RRM2) found in squamous cell carcinoma antigen recognized by T-cells 3 (SART3) and similar proteins; This subfamily corresponds to the RRM2 of SART3, also termed Tat-interacting protein of 110 kDa (Tip110), is an RNA-binding protein expressed in the nucleus of the majority of proliferating cells, including normal cells and malignant cells, but not in normal tissues except for the testes and fetal liver. It is involved in the regulation of mRNA splicing probably via its complex formation with RNA-binding protein with a serine-rich domain (RNPS1), a pre-mRNA-splicing factor. SART3 has also been identified as a nuclear Tat-interacting protein that regulates Tat transactivation activity through direct interaction and functions as an important cellular factor for HIV-1 gene expression and viral replication. In addition, SART3 is required for U6 snRNP targeting to Cajal bodies. It binds specifically and directly to the U6 snRNA, interacts transiently with the U6 and U4/U6 snRNPs, and promotes the reassembly of U4/U6 snRNPs after splicing in vitro. SART3 contains an N-terminal half-a-tetratricopeptide repeat (HAT)-rich domain, a nuclearlocalization signal (NLS) domain, and two C-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45554213 722 EINKIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAISNP 801
Cdd:cd12392   1 EKNKLFVKGLPFSCTKEELEELFKQHGTVKDVRLVTYRNGKPKGLAYVEYENEADASQAVLKTDGTEIKDHTISVAISNP 80

                .
gi 45554213 802 P 802
Cdd:cd12392  81 P 81

RNA recognition motif. (a.k.a. RRM, RBD, or RNP domain); The RRM motif is probably diagnostic of an RNA binding protein. RRMs are found in a variety of RNA binding proteins, including various hnRNP proteins, proteins implicated in regulation of alternative splicing, and protein components of snRNPs. The motif also appears in a few single stranded DNA binding proteins. The RRM structure consists of four strands and two helices arranged in an alpha/beta sandwich, with a third helix present during RNA binding in some cases The C-terminal beta strand (4th strand) and final helix are hard to align and have been omitted in the SEED alignment The LA proteins have an N terminal rrm which is included in the seed. There is a second region towards the C terminus that has some features characteriztic of a rrm but does not appear to have the important structural core of a rrm. The LA proteins are one of the main autoantigens in Systemic lupus erythematosus (SLE), an autoimmune disease.

                          10        20        30        40        50        60
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....
gi 45554213   726 IFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNI 794
Cdd:pfam00076   1 LFVGNLPPDTTEEDLKDLFSKFGPIKSIRLVRDETGRSKGFAFVEFEDEEDAEKAIEALNGKELGGREL 69

RNA recognition motif (RRM) domain [Translation, ribosomal structure and biogenesis];

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45554213 724 NKIFVRNLHPACSKEELHELFSPFGTIKDVRLV-HKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAISNPP 802
Cdd:COG0724   2 MKIYVGNLPYSVTEEDLRELFSEYGEVTSVKLItDRETGRSRGFGFVEMPDDEEAQAAIEALNGAELMGRTLKVNEARPR 81

                ...
gi 45554213 803 PRG 805
Cdd:COG0724  82 EER 84

RNA recognition motif 2 (RRM2) found in yeast multiple RNA-binding domain-containing protein 1 (MRD1) and similar proteins; This subgroup corresponds to the RRM2 of MRD1 which is encoded by a novel yeast gene MRD1 (multiple RNA-binding domain). It is well-conserved in yeast and its homologs exist in all eukaryotes. MRD1 is present in the nucleolus and the nucleoplasm. It interacts with the 35 S precursor rRNA (pre-rRNA) and U3 small nucleolar RNAs (snoRNAs). It is essential for the initial processing at the A0-A2 cleavage sites in the 35 S pre-rRNA. MRD1 contains 5 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), which may play an important structural role in organizing specific rRNA processing events.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|.
gi 45554213 722 EINKIFVRNLHPACSKEELHELFSPFGTIKDVRLV-HKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKG 791
Cdd:cd12566   1 ETGRLFLRNLPYSTKEDDLQKLFSKFGEVSEVHVPiDKKTKKSKGFAYVLFLDPEDAVQAYNELDGKVFQG 71

RNA recognition motif (RRM) found in the Aly/REF family; This subfamily corresponds to the RRM of Aly/REF family which includes THO complex subunit 4 (THOC4, also termed Aly/REF), S6K1 Aly/REF-like target (SKAR, also termed PDIP3 or PDIP46) and similar proteins. THOC4 is an mRNA transporter protein with a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). It is involved in RNA transportation from the nucleus, and was initially identified as a transcription coactivator of LEF-1 and AML-1 for the TCRalpha enhancer function. In addition, THOC4 specifically binds to rhesus (RH) promoter in erythroid, and might be a novel transcription cofactor for erythroid-specific genes. SKAR shows high sequence homology with THOC4 and possesses one RRM as well. SKAR is widely expressed and localizes to the nucleus. It may be a critical player in the function of S6K1 in cell and organism growth control by binding the activated, hyperphosphorylated form of S6K1 but not S6K2. Furthermore, SKAR functions as a protein partner of the p50 subunit of DNA polymerase delta. In addition, SKAR may have particular importance in pancreatic beta cell size determination and insulin secretion.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAI 798
Cdd:cd12418   2 RVRVSNLHPDVTEEDLRELFGRVGPVKSVKINYDRSGRSTGTAYVVFERPEDAEKAIKQFDGVLLDGQPMKVEL 75

RNA recognition motif (RRM) found in AZoospermia (DAZ) autosomal homologs, DAZL (DAZ-like) and BOULE; This subfamily corresponds to the RRM domain of two Deleted in AZoospermia (DAZ) autosomal homologs, DAZL (DAZ-like) and BOULE. BOULE is the founder member of the family and DAZL arose from BOULE in an ancestor of vertebrates. The DAZ gene subsequently originated from a duplication transposition of the DAZL gene. Invertebrates contain a single DAZ homolog, BOULE, while vertebrates, other than catarrhine primates, possess both BOULE and DAZL genes. The catarrhine primates possess BOULE, DAZL, and DAZ genes. The family members encode closely related RNA-binding proteins that are required for fertility in numerous organisms. These proteins contain an RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a varying number of copies of a DAZ motif, believed to mediate protein-protein interactions. DAZL and BOULE contain a single copy of the DAZ motif, while DAZ proteins can contain 8-24 copies of this repeat. Although their specific biochemical functions remain to be investigated, DAZL proteins may interact with poly(A)-binding proteins (PABPs), and act as translational activators of specific mRNAs during gametogenesis.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 45554213 724 NKIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKG--MNISVAI 798
Cdd:cd12412   3 NRIFVGGIDWDTTEEELREFFSKFGKVKDVKIIKDRAGVSKGYGFVTFETQEDAEKIQKWGANLVFKGkkLNVGPAI 79

RNA recognition motif (RRM) found in heterogeneous nuclear ribonucleoprotein C (hnRNP C)-related proteins; This subfamily corresponds to the RRM in the hnRNP C-related protein family, including hnRNP C proteins, Raly, and Raly-like protein (RALYL). hnRNP C proteins, C1 and C2, are produced by a single coding sequence. They are the major constituents of the heterogeneous nuclear RNA (hnRNA) ribonucleoprotein (hnRNP) complex in vertebrates. They bind hnRNA tightly, suggesting a central role in the formation of the ubiquitous hnRNP complex; they are involved in the packaging of the hnRNA in the nucleus and in processing of pre-mRNA such as splicing and 3'-end formation. Raly, also termed autoantigen p542, is an RNA-binding protein that may play a critical role in embryonic development. The biological role of RALYL remains unclear. It shows high sequence homology with hnRNP C proteins and Raly. Members of this family are characterized by an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal auxiliary domain. The Raly proteins contain a glycine/serine-rich stretch within the C-terminal regions, which is absent in the hnRNP C proteins. Thus, the Raly proteins represent a newly identified class of evolutionarily conserved autoepitopes.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|...
gi 45554213 725 KIFVRNLHPA-CSKEELHELFSPFGTIKDVRLvhklnkqFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:cd12341   2 RIFVGNLPTDqMTKEDLEEIFSKYGKILGISL-------HKGYGFVQFDNEEDARAAVAGENGRTIKGQRLDI 67

RNA recognition motif 1 (RRM1) found in yeast nucleolar protein 3 (Npl3p) and similar proteins; This subfamily corresponds to the RRM1 of Npl3p, also termed mitochondrial targeting suppressor 1 protein, or nuclear polyadenylated RNA-binding protein 1. Npl3p is a major yeast RNA-binding protein that competes with 3'-end processing factors, such as Rna15, for binding to the nascent RNA, protecting the transcript from premature termination and coordinating transcription termination and the packaging of the fully processed transcript for export. It specifically recognizes a class of G/U-rich RNAs. Npl3p is a multi-domain protein containing two central RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), separated by a short linker and a C-terminal domain rich in glycine, arginine and serine residues.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKlnkqfKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:cd12340   1 RLFVRPFPPDTSESAIREIFSPYGPVKEVKMLSD-----SNFAFVEFEELEDAIRAKDSVHGRVLNNEPLYV 67

RNA recognition motif (RRM) found in RNA-binding protein RBM8A, RBM8B nd similar proteins; This subfamily corresponds to the RRM of RBM8, also termed binder of OVCA1-1 (BOV-1), or RNA-binding protein Y14, which is one of the components of the exon-exon junction complex (EJC). It has two isoforms, RBM8A and RBM8B, both of which are identical except that RBM8B is 16 amino acids shorter at its N-terminus. RBM8, together with other EJC components (such as Magoh, Aly/REF, RNPS1, Srm160, and Upf3), plays critical roles in postsplicing processing, including nuclear export and cytoplasmic localization of the mRNA, and the nonsense-mediated mRNA decay (NMD) surveillance process. RBM8 binds to mRNA 20-24 nucleotides upstream of a spliced exon-exon junction. It is also involved in spliced mRNA nuclear export, and the process of nonsense-mediated decay of mRNAs with premature stop codons. RBM8 forms a specific heterodimer complex with the EJC protein Magoh which then associates with Aly/REF, RNPS1, DEK, and SRm160 on the spliced mRNA, and inhibits ATP turnover by eIF4AIII, thereby trapping the EJC core onto RNA. RBM8 contains an N-terminal putative bipartite nuclear localization signal, one RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), in the central region, and a C-terminal serine-arginine rich region (SR domain) and glycine-arginine rich region (RG domain).

                        10        20        30        40        50        60        70        80
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVRLvhKLNKQ---FKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV--AISN 800
Cdd:cd12324   9 IFVTGVHEEAQEEDIHDKFAEFGEIKNLHL--NLDRRtgfVKGYALVEYETKKEAQAAIEGLNGKELLGQTISVdwAFVK 86

                ..
gi 45554213 801 PP 802
Cdd:cd12324  87 GP 88

RNA recognition motif 1 (RRM1) and 2 (RRM2) found in RRM-containing coactivator activator/modulator (CoAA) and similar proteins; This subfamily corresponds to the RRM in CoAA (also known as RBM14 or PSP2) and RNA-binding protein 4 (RBM4). CoAA is a heterogeneous nuclear ribonucleoprotein (hnRNP)-like protein identified as a nuclear receptor coactivator. It mediates transcriptional coactivation and RNA splicing effects in a promoter-preferential manner, and is enhanced by thyroid hormone receptor-binding protein (TRBP). CoAA contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a TRBP-interacting domain. RBM4 is a ubiquitously expressed splicing factor with two isoforms, RBM4A (also known as Lark homolog) and RBM4B (also known as RBM30), which are very similar in structure and sequence. RBM4 may also function as a translational regulator of stress-associated mRNAs as well as play a role in micro-RNA-mediated gene regulation. RBM4 contains two N-terminal RRMs, a CCHC-type zinc finger, and three alanine-rich regions within their C-terminal regions. This family also includes Drosophila RNA-binding protein lark (Dlark), a homolog of human RBM4. It plays an important role in embryonic development and in the circadian regulation of adult eclosion. Dlark shares high sequence similarity with RBM4 at the N-terminal region. However, Dlark has three proline-rich segments instead of three alanine-rich segments within the C-terminal region.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVhklnKQFkgiAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:cd12343   1 KIFVGNLPDAATSEELRALFEKYGKVTECDIV----KNY---AFVHMEKEEDAEDAIKALNGYEFMGSRINV 65

RNA recognition motif 1 (RRM1) found in RNA-binding protein 28 (RBM28) and similar proteins; This subfamily corresponds to the RRM1 of RBM28 and Nop4p. RBM28 is a specific nucleolar component of the spliceosomal small nuclear ribonucleoproteins (snRNPs), possibly coordinating their transition through the nucleolus. It specifically associates with U1, U2, U4, U5, and U6 small nuclear RNAs (snRNAs), and may play a role in the maturation of both small nuclear and ribosomal RNAs. RBM28 has four RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and an extremely acidic region between RRM2 and RRM3. The family also includes nucleolar protein 4 (Nop4p or Nop77p) encoded by YPL043W from Saccharomyces cerevisiae. It is an essential nucleolar protein involved in processing and maturation of 27S pre-rRNA and biogenesis of 60S ribosomal subunits. Nop4p also contains four RRMs.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*...
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNK-QFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAISNP 801
Cdd:cd12413   1 TLFVRNLPYDTTDEQLEELFSDVGPVKRCFVVKDKGKdKCRGFGYVTFALAEDAQRALEEVKGKKFGGRKIKVELAKK 78

RNA recognition motif 4 (RRM4) found in type I polyadenylate-binding proteins; This subfamily corresponds to the RRM4 of type I poly(A)-binding proteins (PABPs), highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in theThe CD corresponds to the RRM. regulation of poly(A) tail length during the polyadenylation reaction, translation initiation, mRNA stabilization by influencing the rate of deadenylation and inhibition of mRNA decapping. The family represents type I polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 1 (PABP-1 or PABPC1), polyadenylate-binding protein 3 (PABP-3 or PABPC3), polyadenylate-binding protein 4 (PABP-4 or APP-1 or iPABP), polyadenylate-binding protein 5 (PABP-5 or PABPC5), polyadenylate-binding protein 1-like (PABP-1-like or PABPC1L), polyadenylate-binding protein 1-like 2 (PABPC1L2 or RBM32), polyadenylate-binding protein 4-like (PABP-4-like or PABPC4L), yeast polyadenylate-binding protein, cytoplasmic and nuclear (PABP or ACBP-67), and similar proteins. PABP-1 is an ubiquitously expressed multifunctional protein that may play a role in 3' end formation of mRNA, translation initiation, mRNA stabilization, protection of poly(A) from nuclease activity, mRNA deadenylation, inhibition of mRNA decapping, and mRNP maturation. Although PABP-1 is thought to be a cytoplasmic protein, it is also found in the nucleus. PABP-1 may be involved in nucleocytoplasmic trafficking and utilization of mRNP particles. PABP-1 contains four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), a less well conserved linker region, and a proline-rich C-terminal conserved domain (CTD). PABP-3 is a testis-specific poly(A)-binding protein specifically expressed in round spermatids. It is mainly found in mammalian and may play an important role in the testis-specific regulation of mRNA homeostasis. PABP-3 shows significant sequence similarity to PABP-1. However, it binds to poly(A) with a lower affinity than PABP-1. Moreover, PABP-1 possesses an A-rich sequence in its 5'-UTR and allows binding of PABP and blockage of translation of its own mRNA. In contrast, PABP-3 lacks the A-rich sequence in its 5'-UTR. PABP-4 is an inducible poly(A)-binding protein (iPABP) that is primarily localized to the cytoplasm. It shows significant sequence similarity to PABP-1 as well. The RNA binding properties of PABP-1 and PABP-4 appear to be identical. PABP-5 is encoded by PABPC5 gene within the X-specific subinterval, and expressed in fetal brain and in a range of adult tissues in mammalian, such as ovary and testis. It may play an important role in germ cell development. Moreover, unlike other PABPs, PABP-5 contains only four RRMs, but lacks both the linker region and the CTD. PABP-1-like and PABP-1-like 2 are the orthologs of PABP-1. PABP-4-like is the ortholog of PABP-5. Their cellular functions remain unclear. The family also includes the yeast PABP, a conserved poly(A) binding protein containing poly(A) tails that can be attached to the 3'-ends of mRNAs. The yeast PABP and its homologs may play important roles in the initiation of translation and in mRNA decay. Like vertebrate PABP-1, the yeast PABP contains four RRMs, a linker region, and a proline-rich CTD as well. The first two RRMs are mainly responsible for specific binding to poly(A). The proline-rich region may be involved in protein-protein interactions.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45554213 724 NKIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAI 798
Cdd:cd12381   2 VNLYVKNLDDTIDDEKLREEFSPFGTITSAKVMTDEGGRSKGFGFVCFSSPEEATKAVTEMNGRIIGGKPLYVAL 76

RNA recognition motif (RRM) found in serine/arginine-rich splicing factor 3 (SRSF3) and similar proteins; This subfamily corresponds to the RRM of two serine/arginine (SR) proteins, serine/arginine-rich splicing factor 3 (SRSF3) and serine/arginine-rich splicing factor 7 (SRSF7). SRSF3, also termed pre-mRNA-splicing factor SRp20, modulates alternative splicing by interacting with RNA cis-elements in a concentration- and cell differentiation-dependent manner. It is also involved in termination of transcription, alternative RNA polyadenylation, RNA export, and protein translation. SRSF3 is critical for cell proliferation, and tumor induction and maintenance. It can shuttle between the nucleus and cytoplasm. SRSF7, also termed splicing factor 9G8, plays a crucial role in both constitutive splicing and alternative splicing of many pre-mRNAs. Its localization and functions are tightly regulated by phosphorylation. SRSF7 is predominantly present in the nuclear and can shuttle between nucleus and cytoplasm. It cooperates with the export protein, Tap/NXF1, helps mRNA export to the cytoplasm, and enhances the expression of unspliced mRNA. Moreover, SRSF7 inhibits tau E10 inclusion through directly interacting with the proximal downstream intron of E10, a clustering region for frontotemporal dementia with Parkinsonism (FTDP) mutations. Both SRSF3 and SRSF7 contain a single N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal RS domain rich in serine-arginine dipeptides. The RRM domain is involved in RNA binding, and the RS domain has been implicated in protein shuttling and protein-protein interactions.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVhklnKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAISNP 801
Cdd:cd12373   1 KVYVGNLGPRVTKRELEDAFEKYGPLRNVWVA----RNPPGFAFVEFEDPRDAEDAVRALDGRRICGSRVRVELSRG 73

RNA recognition motif 1 (RRM1) found in yeast multiple RNA-binding domain-containing protein 1 (MRD1) and similar proteins; This subgroup corresponds to the RRM1 of MRD1 which is encoded by a novel yeast gene MRD1 (multiple RNA-binding domain). It is well-conserved in yeast and its homologs exist in all eukaryotes. MRD1 is present in the nucleolus and the nucleoplasm. It interacts with the 35 S precursor rRNA (pre-rRNA) and U3 small nucleolar RNAs (snoRNAs). MRD1 is essential for the initial processing at the A0-A2 cleavage sites in the 35 S pre-rRNA. It contains 5 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), which may play an important structural role in organizing specific rRNA processing events.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAIS 799
Cdd:cd12565   2 RIIVKNLPKYVTEKRLKEHFSKKGEITDVKVMRTKDGKSRRFGFIGFKSEEEAQKAVKYFNKTFIDTSKISVEFA 76

RNA recognition motif 1 (RRM1) found in nucleolin-like proteins mainly from plants; This subfamily corresponds to the RRM1 of a group of plant nucleolin-like proteins, including nucleolin 1 (also termed protein nucleolin like 1) and nucleolin 2 (also termed protein nucleolin like 2, or protein parallel like 1). They play roles in the regulation of ribosome synthesis and in the growth and development of plants. Like yeast nucleolin, nucleolin-like proteins possess two RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVRLVHKL-NKQFKGIAYVEFEKPGEAQRAVAgRDGCLFKGMNISVAISNP 801
Cdd:cd12450   2 LFVGNLSWSATQDDLENFFSDCGEVVDVRIAMDRdDGRSKGFGHVEFASAESAQKALE-KSGQDLGGREIRLDLANE 77

RNA recognition motif in type II polyadenylate-binding proteins; This subfamily corresponds to the RRM of type II polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 2 (PABP-2 or PABPN1), embryonic polyadenylate-binding protein 2 (ePABP-2 or PABPN1L) and similar proteins. PABPs are highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in the regulation of poly(A) tail length during the polyadenylation reaction, translation initiation, mRNA stabilization by influencing the rate of deadenylation and inhibition of mRNA decapping. ePABP-2 is predominantly located in the cytoplasm and PABP-2 is located in the nucleus. In contrast to the type I PABPs containing four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), the type II PABPs contains a single highly-conserved RRM. This subfamily also includes Saccharomyces cerevisiae RBP29 (SGN1, YIR001C) gene encoding cytoplasmic mRNA-binding protein Rbp29 that binds preferentially to poly(A). Although not essential for cell viability, Rbp29 plays a role in modulating the expression of cytoplasmic mRNA. Like other type II PABPs, Rbp29 contains one RRM only.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVR-LVHKLNKQFKGIAYVEFEKPGEAQRAVAgRDGCLFKGMNISV 796
Cdd:cd12306   2 IYVGNVDYGTTPEELQAHFKSCGTINRVTiLCDKFTGQPKGFAYIEFVDKSSVENALL-LNESEFRGRQIKV 72

RNA recognition motif 1 (RRM1) found in RNA-binding protein 45 (RBM45) and similar proteins; This subfamily corresponds to the RRM1 of RBM45, also termed developmentally-regulated RNA-binding protein 1 (DRB1), a new member of RNA recognition motif (RRM)-type neural RNA-binding proteins, which expresses under spatiotemporal control. It is encoded by gene drb1 that is expressed in neurons, not in glial cells. RBM45 predominantly localizes in cytoplasm of cultured cells and specifically binds to poly(C) RNA. It could play an important role during neurogenesis. RBM45 carries four RRMs, also known as RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*..
gi 45554213 735 CSK----EELHELFSPFGTIKDVRLVH-KLNKQFKGIAYVEFEKPGEAQRAVAGRDG 786
Cdd:cd12366  10 CSKsvteDDLREAFSPFGEIQDIWVVKdKQTKESKGIAYVKFAKSSQAARAMEEMHG 66

RNA recognition motif (RRM) found in nucleolar protein 8 (NOL8) and similar proteins; This model corresponds to the RRM of NOL8 (also termed Nop132) encoded by a novel NOL8 gene that is up-regulated in the majority of diffuse-type, but not intestinal-type, gastric cancers. Thus, NOL8 may be a good molecular target for treatment of diffuse-type gastric cancer. Also, NOL8 is a phosphorylated protein that contains an N-terminal RNA recognition motif (RRM), also known as RBD (RNA binding domain) or RNP (ribonucleoprotein domain), suggesting NOL8 is likely to function as a novel RNA-binding protein. It may be involved in regulation of gene expression at the post-transcriptional level or in ribosome biogenesis in cancer cells.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....*..
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFE-KPGEAQRAVAGRDGCLFKG 791
Cdd:cd12226   2 LFVGGLSPSITEDDLERRFSRFGTVSDVEIIRKKDAPDRGFAYIDLRtSEAALQKCLSTLNGVKWKG 68

RNA recognition motif (RRM) found in eukaryotic translation initiation factor 3 subunit G (eIF-3G) and similar proteins; This subfamily corresponds to the RRM of eIF-3G and similar proteins. eIF-3G, also termed eIF-3 subunit 4, or eIF-3-delta, or eIF3-p42, or eIF3-p44, is the RNA-binding subunit of eIF3, a large multisubunit complex that plays a central role in the initiation of translation by binding to the 40 S ribosomal subunit and promoting the binding of methionyl-tRNAi and mRNA. eIF-3G binds 18 S rRNA and beta-globin mRNA, and therefore appears to be a nonspecific RNA-binding protein. eIF-3G is one of the cytosolic targets and interacts with mature apoptosis-inducing factor (AIF). eIF-3G contains one RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). This family also includes yeast eIF3-p33, a homolog of vertebrate eIF-3G, plays an important role in the initiation phase of protein synthesis in yeast. It binds both, mRNA and rRNA, fragments due to an RRM near its C-terminus.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|
gi 45554213 728 VRNLHPACSKEELHELFSPFGTIKDVRLV-HKLNKQFKGIAYVEFEKPGEAQRAVAGRDG 786
Cdd:cd12408   4 VTNLSEDATEEDLRELFRPFGPISRVYLAkDKETGQSKGFAFVTFETREDAERAIEKLNG 63

RNA recognition motif (RRM) found in eukaryotic RNA-binding protein 18 and similar proteins; This subfamily corresponds to the RRM of RBM18, a putative RNA-binding protein containing a well-conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). The biological role of RBM18 remains unclear.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVR-LVHK---LNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:cd12355   1 RLWIGNLDPRLTEYHLLKLLSKYGKIKKFDfLFHKtgpLKGQPRGYCFVTFETKEEAEKAIECLNGKLALGKKLVV 76

RNA recognition motif 2 (RRM2) found in vertebrate RRM-containing coactivator activator/modulator (CoAA); This subgroup corresponds to the RRM2 of CoAA, also termed RNA-binding protein 14 (RBM14), or paraspeckle protein 2 (PSP2), or synaptotagmin-interacting protein (SYT-interacting protein), a heterogeneous nuclear ribonucleoprotein (hnRNP)-like protein identified as a nuclear receptor coactivator. It mediates transcriptional coactivation and RNA splicing effects in a promoter-preferential manner and is enhanced by thyroid hormone receptor-binding protein (TRBP). CoAA contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a TRBP-interacting domain. It stimulates transcription through its interactions with coactivators, such as TRBP and CREB-binding protein CBP/p300, via the TRBP-interacting domain and interaction with an RNA-containing complex, such as DNA-dependent protein kinase-poly(ADP-ribose) polymerase complexes, via the RRMs.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVhklnkqfKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:cd12609   2 KIFVGNVSATCTSDELRGLFEEFGRVVECDKV-------KDYAFVHMEREEEALAAIEALNGKEVKGRRINV 66

RNA recognition motif 2 (RRM2) found found in type I polyadenylate-binding proteins; This subfamily corresponds to the RRM2 of type I poly(A)-binding proteins (PABPs), highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in the regulation of poly(A) tail length during the polyadenylation reaction, translation initiation, mRNA stabilization by influencing the rate of deadenylation and inhibition of mRNA decapping. The family represents type I polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 1 (PABP-1 or PABPC1), polyadenylate-binding protein 3 (PABP-3 or PABPC3), polyadenylate-binding protein 4 (PABP-4 or APP-1 or iPABP), polyadenylate-binding protein 5 (PABP-5 or PABPC5), polyadenylate-binding protein 1-like (PABP-1-like or PABPC1L), polyadenylate-binding protein 1-like 2 (PABPC1L2 or RBM32), polyadenylate-binding protein 4-like (PABP-4-like or PABPC4L), yeast polyadenylate-binding protein, cytoplasmic and nuclear (PABP or ACBP-67), and similar proteins. PABP-1 is a ubiquitously expressed multifunctional protein that may play a role in 3' end formation of mRNA, translation initiation, mRNA stabilization, protection of poly(A) from nuclease activity, mRNA deadenylation, inhibition of mRNA decapping, and mRNP maturation. Although PABP-1 is thought to be a cytoplasmic protein, it is also found in the nucleus. PABP-1 may be involved in nucleocytoplasmic trafficking and utilization of mRNP particles. PABP-1 contains four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), a less well conserved linker region, and a proline-rich C-terminal conserved domain (CTD). PABP-3 is a testis-specific poly(A)-binding protein specifically expressed in round spermatids. It is mainly found in mammalian and may play an important role in the testis-specific regulation of mRNA homeostasis. PABP-3 shows significant sequence similarity to PABP-1. However, it binds to poly(A) with a lower affinity than PABP-1. Moreover, PABP-1 possesses an A-rich sequence in its 5'-UTR and allows binding of PABP and blockage of translation of its own mRNA. In contrast, PABP-3 lacks the A-rich sequence in its 5'-UTR. PABP-4 is an inducible poly(A)-binding protein (iPABP) that is primarily localized to the cytoplasm. It shows significant sequence similarity to PABP-1 as well. The RNA binding properties of PABP-1 and PABP-4 appear to be identical. PABP-5 is encoded by PABPC5 gene within the X-specific subinterval, and expressed in fetal brain and in a range of adult tissues in mammalian, such as ovary and testis. It may play an important role in germ cell development. Unlike other PABPs, PABP-5 contains only four RRMs, but lacks both the linker region and the CTD. PABP-1-like and PABP-1-like 2 are the orthologs of PABP-1. PABP-4-like is the ortholog of PABP-5. Their cellular functions remain unclear. The family also includes the yeast PABP, a conserved poly(A) binding protein containing poly(A) tails that can be attached to the 3'-ends of mRNAs. The yeast PABP and its homologs may play important roles in the initiation of translation and in mRNA decay. Like vertebrate PABP-1, the yeast PABP contains four RRMs, a linker region, and a proline-rich CTD as well. The first two RRMs are mainly responsible for specific binding to poly(A). The proline-rich region may be involved in protein-protein interactions.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVA 797
Cdd:cd12379   5 IFIKNLDKSIDNKALYDTFSAFGNILSCKVATDENGGSKGYGFVHFETEEAAERAIEKVNGMLLNGKKVFVG 76

RNA recognition motif 1 (RRM1) and 2 (RRM2) found in CELF/Bruno-like family of RNA binding proteins and plant flowering time control protein FCA; This subfamily corresponds to the RRM1 and RRM2 domains of the CUGBP1 and ETR-3-like factors (CELF) as well as plant flowering time control protein FCA. CELF, also termed BRUNOL (Bruno-like) proteins, is a family of structurally related RNA-binding proteins involved in regulation of pre-mRNA splicing in the nucleus, and control of mRNA translation and deadenylation in the cytoplasm. The family contains six members: CELF-1 (also known as BRUNOL-2, CUG-BP1, NAPOR, EDEN-BP), CELF-2 (also known as BRUNOL-3, ETR-3, CUG-BP2, NAPOR-2), CELF-3 (also known as BRUNOL-1, TNRC4, ETR-1, CAGH4, ER DA4), CELF-4 (BRUNOL-4), CELF-5 (BRUNOL-5) and CELF-6 (BRUNOL-6). They all contain three highly conserved RNA recognition motifs (RRMs), also known as RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains): two consecutive RRMs (RRM1 and RRM2) situated in the N-terminal region followed by a linker region and the third RRM (RRM3) close to the C-terminus of the protein. The low sequence conservation of the linker region is highly suggestive of a large variety in the co-factors that associate with the various CELF family members. Based on both, sequence similarity and function, the CELF family can be divided into two subfamilies, the first containing CELFs 1 and 2, and the second containing CELFs 3, 4, 5, and 6. The different CELF proteins may act through different sites on at least some substrates. Furthermore, CELF proteins may interact with each other in varying combinations to influence alternative splicing in different contexts. This subfamily also includes plant flowering time control protein FCA that functions in the posttranscriptional regulation of transcripts involved in the flowering process. FCA contains two RRMs, and a WW protein interaction domain.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*...
gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLV-HKLNKQFKGIAYVEFEKPGEAQRAV 781
Cdd:cd12361   1 KLFVGMIPKTASEEDVRPLFEQFGNIEEVQILrDKQTGQSKGCAFVTFSTREEALRAI 58

RNA recognition motif (RRM) found in cyclophilin-33 (Cyp33) and similar proteins; This subfamily corresponds to the RRM of Cyp33, also termed peptidyl-prolyl cis-trans isomerase E (PPIase E), or cyclophilin E, or rotamase E. Cyp33 is a nuclear RNA-binding cyclophilin with an N-terminal RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), and a C-terminal PPIase domain. Cyp33 possesses RNA-binding activity and preferentially binds to polyribonucleotide polyA and polyU, but hardly to polyG and polyC. It binds specifically to mRNA, which can stimulate its PPIase activity. Moreover, Cyp33 interacts with the third plant homeodomain (PHD3) zinc finger cassette of the mixed lineage leukemia (MLL) proto-oncoprotein and a poly-A RNA sequence through its RRM domain. It further mediates downregulation of the expression of MLL target genes HOXC8, HOXA9, CDKN1B, and C-MYC, in a proline isomerase-dependent manner. Cyp33 also possesses a PPIase activity that catalyzes cis-trans isomerization of the peptide bond preceding a proline, which has been implicated in the stimulation of folding and conformational changes in folded and unfolded proteins. The PPIase activity can be inhibited by the immunosuppressive drug cyclosporin A.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVRL-VHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAIS 799
Cdd:cd12347   1 LYVGGLAEEVDEKVLHAAFIPFGDIVDIQIpLDYETEKHRGFAFVEFEEAEDAAAAIDNMNESELFGRTIRVNLA 75

RNA recognition motif (RRM) found in heterogeneous nuclear ribonucleoprotein (hnRNP) H protein family, epithelial splicing regulatory proteins (ESRPs), Drosophila RNA-binding protein Fusilli, RNA-binding protein 12 (RBM12) and similar proteins; The family includes RRM domains in the hnRNP H protein family, G-rich sequence factor 1 (GRSF-1), ESRPs (also termed RBM35), Drosophila Fusilli, RBM12 (also termed SWAN), RBM12B, RBM19 (also termed RBD-1) and similar proteins. The hnRNP H protein family includes hnRNP H (also termed mcs94-1), hnRNP H2 (also termed FTP-3 or hnRNP H'), hnRNP F and hnRNP H3 (also termed hnRNP 2H9), which represent a group of nuclear RNA binding proteins that are involved in pre-mRNA processing. GRSF-1 is a cytoplasmic poly(A)+ mRNA binding protein which interacts with RNA in a G-rich element-dependent manner. It may function in RNA packaging, stabilization of RNA secondary structure, or other macromolecular interactions. ESRP1 (also termed RBM35A) and ESRP2 (also termed RBM35B) are epithelial-specific RNA binding proteins that promote splicing of the epithelial variant of fibroblast growth factor receptor 2 (FGFR2), ENAH (also termed hMena), CD44 and CTNND1 (also termed p120-Catenin) transcripts. Fusilli shows high sequence homology to ESRPs. It can regulate endogenous FGFR2 splicing and functions as a splicing factor. The biological roles of both, RBM12 and RBM12B, remain unclear. RBM19 is a nucleolar protein conserved in eukaryotes. It is involved in ribosome biogenesis by processing rRNA. In addition, it is essential for preimplantation development. Members in this family contain 2~6 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....*...
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKD-VRLVHKLNKQFKGIAYVEFEKPGEAQRAVA 782
Cdd:cd12254   2 VRLRGLPFSATEEDIRDFFSGLDIPPDgIHIVYDDDGRPTGEAYVEFASEEDAQRALR 59

RNA recognition motif 3 (RRM3) found found in type I polyadenylate-binding proteins; This subfamily corresponds to the RRM3 of type I poly(A)-binding proteins (PABPs), highly conserved proteins that bind to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. They have been implicated in the regulation of poly(A) tail length during the polyadenylation reaction, translation initiation, mRNA stabilization by influencing the rate of deadenylation and inhibition of mRNA decapping. The family represents type I polyadenylate-binding proteins (PABPs), including polyadenylate-binding protein 1 (PABP-1 or PABPC1), polyadenylate-binding protein 3 (PABP-3 or PABPC3), polyadenylate-binding protein 4 (PABP-4 or APP-1 or iPABP), polyadenylate-binding protein 5 (PABP-5 or PABPC5), polyadenylate-binding protein 1-like (PABP-1-like or PABPC1L), polyadenylate-binding protein 1-like 2 (PABPC1L2 or RBM32), polyadenylate-binding protein 4-like (PABP-4-like or PABPC4L), yeast polyadenylate-binding protein, cytoplasmic and nuclear (PABP or ACBP-67), and similar proteins. PABP-1 is an ubiquitously expressed multifunctional protein that may play a role in 3' end formation of mRNA, translation initiation, mRNA stabilization, protection of poly(A) from nuclease activity, mRNA deadenylation, inhibition of mRNA decapping, and mRNP maturation. Although PABP-1 is thought to be a cytoplasmic protein, it is also found in the nucleus. PABP-1 may be involved in nucleocytoplasmic trafficking and utilization of mRNP particles. PABP-1 contains four copies of RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), a less well conserved linker region, and a proline-rich C-terminal conserved domain (CTD). PABP-3 is a testis-specific poly(A)-binding protein specifically expressed in round spermatids. It is mainly found in mammalian and may play an important role in the testis-specific regulation of mRNA homeostasis. PABP-3 shows significant sequence similarity to PABP-1. However, it binds to poly(A) with a lower affinity than PABP-1. PABP-1 possesses an A-rich sequence in its 5'-UTR and allows binding of PABP and blockage of translation of its own mRNA. In contrast, PABP-3 lacks the A-rich sequence in its 5'-UTR. PABP-4 is an inducible poly(A)-binding protein (iPABP) that is primarily localized to the cytoplasm. It shows significant sequence similarity to PABP-1 as well. The RNA binding properties of PABP-1 and PABP-4 appear to be identical. PABP-5 is encoded by PABPC5 gene within the X-specific subinterval, and expressed in fetal brain and in a range of adult tissues in mammalian, such as ovary and testis. It may play an important role in germ cell development. Moreover, unlike other PABPs, PABP-5 contains only four RRMs, but lacks both the linker region and the CTD. PABP-1-like and PABP-1-like 2 are the orthologs of PABP-1. PABP-4-like is the ortholog of PABP-5. Their cellular functions remain unclear. The family also includes the yeast PABP, a conserved poly(A) binding protein containing poly(A) tails that can be attached to the 3'-ends of mRNAs. The yeast PABP and its homologs may play important roles in the initiation of translation and in mRNA decay. Like vertebrate PABP-1, the yeast PABP contains four RRMs, a linker region, and a proline-rich CTD as well. The first two RRMs are mainly responsible for specific binding to poly(A). The proline-rich region may be involved in protein-protein interactions.

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                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|..
gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVA 797
Cdd:cd12380   4 VYVKNFGEDVDDDELKELFEKYGKITSAKVMKDDSGKSKGFGFVNFENHEAAQKAVEELNGKELNGKKLYVG 75

RNA recognition motif 2 (RRM2) found in U2 large nuclear ribonucleoprotein auxiliary factor U2AF 65 kDa subunit (U2AF65) and similar proteins; This subfamily corresponds to the RRM2 of U2AF65 and dU2AF50. U2AF65, also termed U2AF2, is the large subunit of U2 small nuclear ribonucleoprotein (snRNP) auxiliary factor (U2AF), which has been implicated in the recruitment of U2 snRNP to pre-mRNAs and is a highly conserved heterodimer composed of large and small subunits. U2AF65 specifically recognizes the intron polypyrimidine tract upstream of the 3' splice site and promotes binding of U2 snRNP to the pre-mRNA branchpoint. U2AF65 also plays an important role in the nuclear export of mRNA. It facilitates the formation of a messenger ribonucleoprotein export complex, containing both the NXF1 receptor and the RNA substrate. Moreover, U2AF65 interacts directly and specifically with expanded CAG RNA, and serves as an adaptor to link expanded CAG RNA to NXF1 for RNA export. U2AF65 contains an N-terminal RS domain rich in arginine and serine, followed by a proline-rich segment and three C-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains). The N-terminal RS domain stabilizes the interaction of U2 snRNP with the branch point (BP) by contacting the branch region, and further promotes base pair interactions between U2 snRNA and the BP. The proline-rich segment mediates protein-protein interactions with the RRM domain of the small U2AF subunit (U2AF35 or U2AF1). The RRM1 and RRM2 are sufficient for specific RNA binding, while RRM3 is responsible for protein-protein interactions. The family also includes Splicing factor U2AF 50 kDa subunit (dU2AF50), the Drosophila ortholog of U2AF65. dU2AF50 functions as an essential pre-mRNA splicing factor in flies. It associates with intronless mRNAs and plays a significant and unexpected role in the nuclear export of a large number of intronless mRNAs.

                        10        20        30        40        50        60
                ....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45554213 724 NKIFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNK-QFKGIAYVEFEKPGEAQRAVAGRDG 786
Cdd:cd12231   1 NKLFIGGLPNYLNEDQVKELLQSFGKLKAFNLVKDSATgLSKGYAFCEYVDDNVTDQAIAGLNG 64

ELAV/HuD family splicing factor; This model describes the ELAV/HuD subfamily of splicing factors found in metazoa. HuD stands for the human paraneoplastic encephalomyelitis antigen D of which there are 4 variants in human. ELAV stnds for the Drosophila Embryonic lethal abnormal visual protein. ELAV-like splicing factors are also known in human as HuB (ELAV-like protein 2), HuC (ELAV-like protein 3, Paraneoplastic cerebellar degeneration-associated antigen) and HuR (ELAV-like protein 1). These genes are most closely related to the sex-lethal subfamily of splicing factors found in Dipteran insects (TIGR01659). These proteins contain 3 RNA-recognition motifs (rrm: pfam00076).

                          10        20        30        40        50        60        70        80
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*....|
gi 45554213   705 PANAEAKESNfkyspnmeinkIFVRNLHPACSKEELHELFSPFGTIKDVR-LVHKLNKQFKGIAYVEFEKPGEAQRAVAG 783
Cdd:TIGR01661  82 PSSDSIKGAN-----------LYVSGLPKTMTQHELESIFSPFGQIITSRiLSDNVTGLSKGVGFIRFDKRDEADRAIKT 150

                          90       100       110       120       130       140       150
                  ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....
gi 45554213   784 RDGCLFKGMN--ISVAISNPPPRGTS-AVKPSVA--PKRRVPTSLIPTTLVRQEVAA--KKLRLLLPEPGDISS 850
Cdd:TIGR01661 151 LNGTTPSGCTepITVKFANNPSSSNSkGLLSQLEavQNPQTTRVPLSTILTAAGIGPmhHAAARFRPSAGDFTA 224

RNA recognition motif (RRM) found in eukaryotic translation initiation factor 4H (eIF-4H) and similar proteins; This subfamily corresponds to the RRM of eIF-4H, also termed Williams-Beuren syndrome chromosomal region 1 protein, which, together with elf-4B/eIF-4G, serves as the accessory protein of RNA helicase eIF-4A. eIF-4H contains a well conserved RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain). It stimulates protein synthesis by enhancing the helicase activity of eIF-4A in the initiation step of mRNA translation.

                        10        20        30        40        50        60        70
                ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 45554213 727 FVRNLHPACSKEELHELFSPFgTIKDVRLVH-KLNKQFKGIAYVEFEKPGEAQRAVAgRDGCLFKGMNISVAISN 800
Cdd:cd12401   9 YVGNLPFNTVQGDLDAIFKDL-KVRSVRLVRdRETDKFKGFCYVEFEDLESLKEALE-YDGALFEDRPLRVDIAE 81

RNA recognition motif 1 (RRM1) found in (U)-binding-splicing factor PUF60 and similar proteins; This subfamily corresponds to the RRM1 of PUF60, also termed FUSE-binding protein-interacting repressor (FBP-interacting repressor or FIR), or Ro-binding protein 1 (RoBP1), or Siah-binding protein 1 (Siah-BP1). PUF60 is an essential splicing factor that functions as a poly-U RNA-binding protein required to reconstitute splicing in depleted nuclear extracts. Its function is enhanced through interaction with U2 auxiliary factor U2AF65. PUF60 also controls human c-myc gene expression by binding and inhibiting the transcription factor far upstream sequence element (FUSE)-binding-protein (FBP), an activator of c-myc promoters. PUF60 contains two central RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a C-terminal U2AF (U2 auxiliary factor) homology motifs (UHM) that harbors another RRM and binds to tryptophan-containing linear peptide motifs (UHM ligand motifs, ULMs) in several nuclear proteins. Research indicates that PUF60 binds FUSE as a dimer, and only the first two RRM domains participate in the single-stranded DNA recognition.

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gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVH-KLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:cd12370   2 RVYVGSIYFELGEDTIRQAFAPFGPIKSIDMSWdPVTMKHKGFAFVEYEVPEAAQLALEQMNGVMLGGRNIKV 74

RNA recognition motif 1 (RRM1) found in vertebrate RRM-containing coactivator activator/modulator (CoAA); This subgroup corresponds to the RRM1 of CoAA, also termed RNA-binding protein 14 (RBM14), or paraspeckle protein 2 (PSP2), or synaptotagmin-interacting protein (SYT-interacting protein), a heterogeneous nuclear ribonucleoprotein (hnRNP)-like protein identified as a nuclear receptor coactivator. It mediates transcriptional coactivation and RNA splicing effects in a promoter-preferential manner and is enhanced by thyroid hormone receptor-binding protein (TRBP). CoAA contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), and a TRBP-interacting domain. It stimulates transcription through its interactions with coactivators, such as TRBP and CREB-binding protein CBP/p300, via the TRBP-interacting domain and interaction with an RNA-containing complex, such as DNA-dependent protein kinase-poly(ADP-ribose) polymerase complexes, via the RRMs.

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gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLVhklnKQFkgiAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAIS 799
Cdd:cd12608   2 KIFVGNVDEDTSQEELSALFEPYGAVLSCAVM----KQF---AFVHMRGEAAADRAIRELNGRELHGRALVVEES 69

RNA recognition motif 1 (RRM1) found in plant pre-mRNA-splicing factor SF2 and similar proteins; This subgroup corresponds to the RRM1 of SF2, also termed SR1 protein, a plant serine/arginine (SR)-rich phosphoprotein similar to the mammalian splicing factor SF2/ASF. It promotes splice site switching in mammalian nuclear extracts. SF2 contains two N-terminal RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains), followed by a C-terminal domain rich in proline, serine and lysine residues (PSK domain), a composition reminiscent of histones. This PSK domain harbors a putative phosphorylation site for the mitotic kinase cyclin/p34cdc2.

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gi 45554213 725 KIFVRNLHPACSKEELHELFSPFGTIKDVRLvhKLNKQFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISV 796
Cdd:cd12599   1 RVYVGNLPMDIREREVEDLFSKYGPVVSIDL--KIPPRPPAYAFVEFEDARDAEDAIRGRDGYDFDGHRLRV 70

RNA recognition motif 5 (RRM5) found in RNA-binding protein 19 (RBM19 or RBD-1) and similar proteins; This subfamily corresponds to the RRM5 of RBM19 and RRM4 of MRD1. RBM19, also termed RNA-binding domain-1 (RBD-1), is a nucleolar protein conserved in eukaryotes involved in ribosome biogenesis by processing rRNA and is essential for preimplantation development. It has a unique domain organization containing 6 conserved RNA recognition motifs (RRMs), also termed RBDs (RNA binding domains) or RNPs (ribonucleoprotein domains).

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gi 45554213 726 IFVRNLHPACSKEELHELFSPFGTIKDVRLVHKLNK----QFKGIAYVEFEKPGEAQRAVAGRDGCLFKGMNISVAIS 799
Cdd:cd12318   3 LFVKNLNFKTTEEALKKHFEKCGPIRSVTIAKKKDPkgplLSMGYGFVEFKSPEAAQKALKQLQGTVLDGHALELKIS 80

RNA recognition motif 1 (RRM1) found in La-related protein 7 (LARP7) and similar proteins; This subfamily corresponds to the RRM1 of LARP7, also termed La ribonucleoprotein domain family member 7, or P-TEFb-interaction protein for 7SK stability (PIP7S), an oligopyrimidine-binding protein that binds to the highly conserved 3'-terminal U-rich stretch (3' -UUU-OH) of 7SK RNA. LARP7 is a stable component of the 7SK small nuclear ribonucleoprotein (7SK snRNP). It intimately associates with all the nuclear 7SK and is required for 7SK stability. LARP7 also acts as a negative transcriptional regulator of cellular and viral polymerase II genes, acting by means of the 7SK snRNP system. It plays an essential role in the inhibition of positive transcription elongation factor b (P-TEFb)-dependent transcription, which has been linked to the global control of cell growth and tumorigenesis. LARP7 contains a La motif (LAM) and an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain), at the N-terminal region, which mediates binding to the U-rich 3' terminus of 7SK RNA. LARP7 also carries another putative RRM domain at its C-terminus.