third type I K homology (KH) RNA-binding domain found in the FUBP family RNA/DNA-binding proteins
The far upstream element-binding protein (FUBP) family includes FUBP1-3. FUBP1, also called FBP, or FUSE-binding protein 1, or DNA helicase V, or DH V, binds RNA and single-stranded DNA (ssDNA) and may act both as activator and repressor of transcription. It regulates MYC expression by binding to a single-stranded far-upstream element (FUSE) upstream of the MYC promoter. FUBP2, also called FUSE-binding protein 2, or KH type-splicing regulatory protein (KSRP), or p75, is a single-strand nucleic acid binding protein implicated in a variety of cellular processes, including splicing in the nucleus, mRNA decay, maturation of miRNA, and transcriptional control of proto-oncogenes such as c-myc. It regulates the stability and/or translatability of many mRNA species, encoding immune-relevant proteins, either by binding to AU-rich elements (AREs) of mRNA 3'UTR or by facilitating miRNA biogenesis to target mRNA. FUBP3, also called FUSE-binding protein 3, or MARTA2, was previously shown to mediate dendritic targeting of MAP2 mRNA in neurons. It may interact with single-stranded DNA from the far-upstream element (FUSE) and activate gene expression. It is required for beta-actin mRNA localization. It also interacts with fibroblast growth factor 9 (FGF9) 3'-UTR UG repeats and positively controls FGF9 expression through increasing translation of FGF9 mRNA. FUBP proteins contain four K-homology (KH) RNA-binding domains. The model corresponds to the third one.