| Primary Identifier | IPR000314 | Type | Family |
| Short Name | Gastrin_rcpt |
| description | G protein-coupled receptors (GPCRs) constitute a vast protein family that encompasses a wide range of functions, including various autocrine, paracrine and endocrine processes. They show considerable diversity at the sequence level, on the basis of which they can be separated into distinct groups []. The term clan can be used to describe the GPCRs, as they embrace a group of families for which there are indications of evolutionary relationship, but between which there is no statistically significant similarity in sequence []. The currently known clan members include rhodopsin-like GPCRs (Class A, GPCRA), secretin-like GPCRs (Class B, GPCRB), metabotropic glutamate receptor family (Class C, GPCRC), fungal mating pheromone receptors (Class D, GPCRD), cAMP receptors (Class E, GPCRE) and frizzled/smoothened (Class F, GPCRF) [, , , , ]. GPCRs are major drug targets, and are consequently the subject of considerable research interest. It has been reported that the repertoire of GPCRs for endogenous ligands consists of approximately 400 receptors in humans and mice []. Most GPCRs are identified on the basis of their DNA sequences, rather than the ligand they bind, those that are unmatched to known natural ligands are designated by as orphan GPCRs, or unclassified GPCRs [].The rhodopsin-like GPCRs (GPCRA) represent a widespread protein family that includes hormone, neurotransmitter and light receptors, all of which transduce extracellular signals through interaction with guanine nucleotide-binding (G) proteins. Although their activating ligands vary widely in structure and character, the amino acid sequences of the receptors are very similar and are believed to adopt a common structural framework comprising 7 transmembrane (TM) helices [, , ].Gastrins and cholecystokinins (CCKs) are naturally-occurring peptides that share a common C-terminal sequence, GWMDF; full biological activity resides in this region. The principal physiological role of gastrin is to stimulate acid secretion in the stomach; it also has trophic effects on gastric mucosa. Gastrin is produced from a single gene transcript, and is found predominantly in the stomach and intestine, but also in vagal nerves. The CCKB receptor has a widespread distribution in the CNS and has been implicated in the pathogenesis of panic-anxiety attacks caused by CCK-related peptides. It has a more limited distribution in the periphery, where it is found in smooth muscle and secretory glands. |
