Receptor for somatostatin-14 and -28. This receptor is coupled via pertussis toxin sensitive G proteins to inhibition of adenylyl cyclase. Homodimer and heterodimer with SSTR2. Heterodimerization with SSTR2 inactivates SSTR3 receptor function (By similarity). Internalized into endoplasmic vesicles upon somatostatin-stimulation. Brain, pituitary and pancreas. Phosphorylated. Phosphorylation increases upon somatostatin binding (By similarity). Belongs to the G-protein coupled receptor 1 family.