Secretin receptor family

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

This family is known as Family B, the secretin-receptor family or family 2 of the G-protein-coupled receptors.They have been described in many animal species, but not in plants, fungi or prokaryotes. Three distinct sub-families (B1-B3) are recognized. Many secretin receptors are regulated by peptide hormoness from the glucagon hormone family.

The secretin-like GPCRs include secretin, calcitonin, parathyroid hormone/parathyroid hormone-related peptides and vasoactive intestinal peptide receptors, all of which activate adenylyl cyclase and the phosphatidyl-inositol-calcium  pathway. These receptors have 7 transmembrane helices, like rhodopsin-like GPCRs. However,there is no significant sequence identity between these families: the secretin-like receptors thus bear their own unique '7TM' signature.

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


 * Adenylate cyclase-activating type 1 receptor, pituitary
 * ADCYAP1R1
 * Calcitonin receptor
 * CALCR; CALCRL
 * Corticotropin-releasing hormone receptor
 * CRHR1; CRHR2
 * Glucagon receptor-related
 * GLP1R; GLP2R; GPCR
 * Growth hormone releasing hormone receptor
 * GHRHR
 * Parathyroid hormone receptor
 * PTHR1; PTHR2
 * Secretin receptor
 * SCTR
 * Vasoactive intestinal peptide receptor
 * VIPR1;    VIPR2

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, and brain-specific angiogenesis inhibitor receptors (such as ) amongst others.


 * Brain-specific angiogenesis inhibitor
 * BAI1; BAI2; BAI3
 * CD97 antigen
 * CD97
 * EMR hormone receptor
 * CELSR1; CELSR2; CELSR3; EMR1; EMR2; EMR3; EMR4
 * Gastric inhibitory polypeptide receptor
 * GCGR; GIPR
 * GPR56 orphan receptor
 * GPR56; GPR64; GPR97; GPR110; GPR111; GPR112; GPR113; GPR114; GPR115; GPR123; GPR125; GPR126; GPR128; GPR133; GPR144; GPR157
 * Latrophilin receptor
 * ELTD1; LPHN1; LPHN2; LPHN3

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

Unclassified subfamilies

 * Ig-hepta receptor
 * GPR116

Unclassified members
DREG; HCTR-5; HCTR-6; KPG_003; KPG_006; KPG_008; KPG_009; RESDA1