Conserved Protein Domain Family
PQ-loop

?
pfam04193: PQ-loop 
PQ loop repeat
Members of this family are all membrane bound proteins possessing a pair of repeats each spanning two transmembrane helices connected by a loop. The PQ motif found on loop 2 is critical for the localization of cystinosin to lysosomes. However, the PQ motif appears not to be a general lysosome-targeting motif. It is thought likely to possess a more general function. Most probably this involves a glutamine residue. Family members are membrane transporters since two members, cystinosin and PQLC2, transport cystine and cationic amino acids, respectively, across the lysosomal membrane. The 2nd PQ-loop of cystinosin hosts the substrate-coupled H+ binding site underlying its H+ symport mechanism, suggesting that PQ-loop repeats have functional significance. It is thus likely that PQ-loop-containing proteins act as a family of membrane transporters. Some transport cystine and cationic amino acids, respectively, across the lysosomal membrane. Others transport lysine and or arginine across the lysosomal membrane in order to maintain the acidic homoeostasis.
Statistics
?
PSSM-Id: 398045
Aligned: 214 rows
Threshold Bit Score: 32.8852
Threshold Setting Gi: 81597580
Created: 20-May-2020
Updated: 7-Aug-2020
Structure
?
Aligned Rows:
PubMed ReferencesClick to see Conserved Features Help

Sequence Alignment
?
Format: Row Display: Color Bits: Type Selection:
Q5ZJX0        39 GSALLGLLSIGCFAAAALPQFYQACKTGIMdRALSIYFLLGWLGGDLLNLIGSFLANQLPLQ 100 chicken
EDL45737      23 LNSVFIYSIIVGSCFTKIPQLTKIVSKKNA-AGISFASVYVEILVATSLIVFSIKEKLAIKL 83  malaria parasite P. vivax
A0E5Y5        54 ISRTISILMVAFAIMNQLPQILKIFKSQST-QGISFNSYYTELYLFSFITAYNIYKQTKFIL 114 Paramecium tetraurelia
A0E4V5        58 LSEFISYSIVALSVILKAPQIFKIVQKSKV-TGLSFDSIFFELFVYSFSIAYNVHKGNPWKL 118 Paramecium tetraurelia
Q20157        37 LSRGLGFAITLGSILLFVPQILKIQAARSA-QGISAASQLLALVGAIGTASYSYRSGFVFsg 97  Caenorhabditis elegans
Q29L16        37 LSKGLGLAIIAGSVLVKVPQVLKILNNKSG-EGINIVGVMLDLLAITFHMSYSFMNGYPFSA 97  Drosophila pseudoobscura
Q66I07        46 LSKTMGIFILMGIVIAPLPQICKILWCGSS-YGLCLTSVFLDLMAISTHAAFCYTQNFPIGA 106 zebrafish
EAY06175      27 IWTIVGTVLLIITIVSYIPQPIKIMQKRSS-YGLAPVSTFFSTICLWLIVFNVICLKWEDFV 87  Trichomonas vaginalis G3
Q86I56        29 GGVLLGIFLLVGCCFSIIPQHIKIVKTKSV-VGLSFLWMFLGNINQFSGFINMFVLKFPQVQ 89  Dictyostelium discoideum
XP_001417796  24 SLRVLGAMSFVVSALIGAPQAYKIYARKSS-RGVSFWTLALGNVGGFLCVLNLYVLHYDQIK 84  Ostreococcus lucimarinus CCE9901
| Disclaimer | Privacy statement | Accessibility |
NCBI Home NCBI Search NCBI SiteMap