Somatostatin receptor 4 (IPR001512)

Short name: Somatstn_rcpt_4

Overlapping homologous superfamilies


Family relationships


Somatostatin (SST), also known as somatotropin release-inhibiting factor (SRIF), is a hypothalamic hormone, a pancreatic hormone, and a central and peripheral neurotransmitter. Somatostatin has a wide distribution throughout the central nervous system (CNS) as well as in peripheral tissues, for example in the pituitary, pancreas and stomach. The various actions of somatostatin are mediated by a family of rhodopsin-like G protein-coupled receptors, which comprise of five distinct subtypes: Somatostatin receptor 1 (SSTR1), Somatostatin receptor 2 (SSTR2), Somatostatin receptor 3 (SSTR3), Somatostatin receptor 4 (SSTR4) and Somatostatin receptor 5 (SSTR5) [PMID: 14507421, PMID: 7792934, PMID: 14507421]. These subtypes are widely expressed in many tissues [PMID: 8243278, PMID: 8078491, PMID: 7907795, PMID: 1346068, PMID: 8483934, PMID: 15361490], and frequently multiple subtypes coexist in the same cell [PMID: 10433861]. The somatostatin receptor subtypes also share common signalling pathways, such as the inhibition of adenylyl cyclase [PMID: 10598790, PMID: 1328199], activation of phosphotyrosine phosphatase (PTP), and modulation of mitogen-activated protein kinase (MAPK) through G protein-dependent mechanisms. Some of the subtypes are also coupled to inward rectifying K+ channels (SSTR2, SSTR3, SSTR4, SSTR5) [PMID: 7538774, PMID: 9426226], to voltage-dependent Ca2+ channels (SSTR1, SSTR2) [PMID: 8684611], to an Na+/H+ exchanger (SSTR1), AMPA/kainate glutamate channels (SSTR1, SSTR2), phospholipase C (SSTR2, SSTR5), and phospholipase A2 (SSTR4) [PMID: 10433861].

Amongst the wide spectrum of somatostatin effects, several biological responses have been identified that display absolute or relative subtype selectivity. These include GH secretion (SSTR2 and 5), insulin secretion (SSTR5), glucagon secretion (SSTR2), and immune responses (SSTR2) [PMID: 10433861].

This entry represents SSTR4. It is present in high levels in the pituitary, but is less abundant in the brain and peripheral tissues [PMID: 14966206, PMID: 10804219, PMID: 8243278]. All five human somatostatin receptors expressed in COS-7 cells are coupled to activation of phosphoinositide (PI)-specific PLC-beta; and Ca2+ mobilisation via pertussis toxin-sensitive G protein(s) with an order of potency of SSTR5 > SSTR2 > SSTR3 > SSTR4 > SSTR1 [PMID: 8034040].

GO terms

Biological Process

GO:0007186 G protein-coupled receptor signaling pathway

Molecular Function

GO:0004994 somatostatin receptor activity

Cellular Component

GO:0016021 integral component of membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.