Secretin receptor family

Secretin receptor family

Secretin family of 7 transmembrane receptors
Symbol 7tm_2
Pfam InterPro PROSITE PDOC00559
SCOP SUPERFAMILY OPM superfamily 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.

  • Pituitary adenylate cyclase-activating polypeptide type 1 receptor IPR002285
  • Calcitonin receptor IPR003287
  • IPR003051
  • Glucose-dependent insulinotropic polypeptide receptor/Gastric inhibitory polypeptide receptor IPR001749
  • IPR003290
  • Growth hormone releasing hormone receptor IPR003288
  • Parathyroid hormone receptor IPR002170
  • Secretin receptor IPR002144
  • IPR001571

Subfamily B2

Subfamily B2 contains receptors with long extracellular N-termini, such as the leukocyte cell-surface antigen 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.

  • Diuretic hormone receptor IPR002001

Unclassified subfamilies

  • Ig-hepta receptor IPR008078

Unclassified members

HCTR-5; HCTR-6; KPG_006; KPG_008