Secretin receptor family
|Secretin family of 7 transmembrane receptors|
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.
- Pituitary adenylate cyclase-activating polypeptide type 1 receptor IPR002285
- Calcitonin receptor IPR003287
- Corticotropin-releasing hormone receptor IPR003051
- Glucose-dependent insulinotropic polypeptide receptor/Gastric inhibitory polypeptide receptor IPR001749
- Glucagon receptor IPR003291
- Glucagon receptor-related IPR003290
- Growth hormone releasing hormone receptor IPR003288
- Parathyroid hormone receptor IPR002170
- Secretin receptor IPR002144
- Vasoactive intestinal peptide receptor IPR001571
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 IPR008077
- CD97 antigen IPR003056
- EMR hormone receptor IPR001740
- GPR56 orphan receptor IPR003910
- Latrophilin receptor IPR003924
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.
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