somatostatin receptor type 4, member of the class A family of seven-transmembrane G protein-coupled receptors
G protein-coupled somatostatin receptors (SSTRs) are composed of five distinct subtypes (SSTR1-5) that display strong sequence similarity with opioid receptors. All five receptor subtypes bind the natural somatostatin (somatotropin release inhibiting factor), a polypeptide hormone that regulates a wide variety of physiological functions such as neurotransmission, cell proliferation, contractility of smooth muscle cells, and endocrine signaling as well as inhibition of the release of many secondary hormones. SSTR4 plays a critical role in mediating inflammation. Unlike other SSTRs, SSTR4 subtype is not detected in all pituitary adenomas while it is expressed in the normal human pituitary.
Comment:based on the structures of some class A family members with bound ligands (peptides or chemicals), agonists, or antagonists
Comment:Small-molecule chemical ligands tend to bind deeper within the receptor core, compared to a peptide ligand neurotensin, which binds towards the extracellular surface of its receptor.
Jiyao W et al.(2023). "The conserved domain database in 2023.",