Somatostatin acts at many sites to inhibit the release of many hormones and other secretory proteins. The biological effects of somatostatin are probably mediated by a family of G protein-coupled receptors that are expressed in a tissue-specific manner. SSTR3 is a member of the superfamily of receptors having seven transmembrane segments and is expressed in highest levels in brain and pancreatic islets. SSTR3 is functionally coupled to adenylyl cyclase.
