Secretin receptor family

Secretin receptor family (class B GPCR subfamily^[1]) consists of secretin receptors regulated by peptide hormones from the glucagon hormone family. The family is different from adhesion G protein-coupled receptors.^[2]

Secretin family of 7 transmembrane receptors
Identifiers
Symbol	7tm_2
Pfam	PF00002
InterPro	IPR000832
PROSITE	PDOC00559
TCDB	9.A.14
OPM superfamily	6
OPM protein	4k5y
CDD	cd13952
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

The secretin-receptor family of 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 seven transmembrane helices,^[3][4] 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.^[5]

The secretin-receptor family GPCRs exist in many animal species. Data mining with the Pfam signature has identified members in fungi, although due to their presumed non-hormonal function they are more commonly referred to as Adhesion G protein-coupled receptors, making the Adhesion subfamily the more basal group.^[6] 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 InterPro: IPR002285
  • PACAPR (ADCYAP1R1)
• Calcitonin receptor InterPro: IPR003287
  • CALCR
• Calcitonin receptor-like receptor InterPro: IPR015476
  • CALCRL
• Corticotropin-releasing hormone receptor InterPro: IPR003051
  • CRHR1; CRHR2
• Glucose-dependent insulinotropic polypeptide receptor/Gastric inhibitory polypeptide receptor InterPro: IPR001749
  • GIPR
• Glucagon receptor InterPro: IPR003291
  • GCGR
• Glucagon receptor-related InterPro: IPR003290
  • GLP1R; GLP2R;
• Growth hormone releasing hormone receptor InterPro: IPR003288
  • GHRHR
• Parathyroid hormone receptor InterPro: IPR002170
  • PTHR1; PTHR2
• Secretin receptor InterPro: IPR002144
  • SCTR
• Vasoactive intestinal peptide receptor InterPro: IPR001571
  • 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^[7] and brain-specific angiogenesis inhibitor receptors^[8] amongst others. They are otherwise known as Adhesion G protein-coupled receptors.

• Brain-specific angiogenesis inhibitor InterPro: IPR008077
  • BAI1; BAI2; BAI3
• CD97 antigen InterPro: IPR003056
  • CD97
• EMR hormone receptor InterPro: IPR001740
  • CELSR1; CELSR2; CELSR3; EMR1; EMR2; EMR3; EMR4
• GPR56 orphan receptor InterPro: IPR003910
  • GPR56; GPR64; GPR97; GPR110; GPR111; GPR112; GPR113; GPR114; GPR115; GPR123; GPR125; GPR126; GPR128; GPR133; GPR144; GPR157
• Latrophilin receptor InterPro: IPR003924
  • ELTD1; LPHN1; LPHN2; LPHN3
• Ig-hepta receptor InterPro: IPR008078
  • GPR116

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 InterPro: IPR002001

Unclassified members

HCTR-5; HCTR-6; KPG 006; KPG 008