Secretin receptor family

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Secretin family of 7 transmembrane receptors
220px
Structure of a 31 amino acid fragment of the extracellular N-terminus of the human parathyroid hormone receptor.[1]
Identifiers
Symbol 7tm_2
Pfam PF00002
InterPro IPR000832
PROSITE PDOC00559
SCOP 1bl1
OPM family 6
OPM protein 1fjr

Secretin family of 7 transmembrane receptors is a family of evolutionarily related proteins.[2]

This family is known as Family B, the secretin-receptor family or family 2 of the G-protein-coupled receptors (GPCR). Many secretin receptors are regulated by peptide hormones from the glucagon hormone family.

The secretin-receptor family GPCRs include vasoactive intestinal peptide receptors and receptors for secretin, calcitonin and parathyroid hormone/parathyroid hormone-related peptides. These receptors activate adenylyl cyclase and the phosphatidyl-inositol-calcium pathway. The receptors in this family have 7 transmembrane helices, like rhodopsin-like GPCRs. However, there is no significant sequence identity between these two GPCR families and the secretin-receptor family has its own characteristic 7TM signature.

The secretin-receptor family GPCRs exist in many animal species, but have not been found in plants, fungi or prokaryotes. Three distinct sub-families (B1-B3) are recognized.

Subfamily B1

Subfamily B1 contains classical hormone receptors, such as receptors for secretin and glucagon, that are all involved in cAMP-mediated signalling pathways.

Subfamily B2

Subfamily B2 contains receptors with long extracellular N-termini, such as the leukocyte cell-surface antigen CD97; calcium-independent receptors for latrotoxin (such as UniProt O94910, and brain-specific angiogenesis inhibitor receptors (such as UniProt O14514) amongst others.

Subfamily B3

Subfamily B3 includes Methuselah and other Drosophila proteins. Other than the typical seven-transmembrane region, characteristic structural features include an amino-terminal extracellular domain involved in ligand binding, and an intracellular loop (IC3) required for specific G-protein coupling.

Unclassified subfamilies

Unclassified members

HCTR-5; HCTR-6; KPG_006; KPG_008

References

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  1. PDB 1BL1; Lua error in package.lua at line 80: module 'Module:Citation/CS1/Suggestions' not found.
  2. Harmar AJ (2001). "Family-B G-protein-coupled receptors". Genome Biol. 2 (12): REVIEWS3013. doi:10.1186/gb-2001-2-12-reviews3013. PMC 138994Freely accessible. PMID 11790261.