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. In the brain, primarily observed in the forebrain. Moderate levels found throughout laminae 2-6 of the neocortex and allocortex, and high levels in lamina 2 of the piriform and entorhinal cortices. High levels also present in the cornu ammonis fields of the hippocampus. In the amygdala, highly expressed in the nucleus of the lateral olfactory tract with expression also detected in the rostral portions of the basal magnocellular and lateral nuclei. In the diencephalon, moderate levels observed in the ventromedial and arcuate nuclei of the hypothalamus. In the midbrain, moderate levels found in the lateral portion of the substantia nigra pars reticulata. Phosphorylated. Phosphorylation increases upon somatostatin binding (By similarity). Belongs to the G-protein coupled receptor 1 family.