Isolation and structure of pro-somatostatin: a putative somatostatin precursor from pig hypothalamus.

Abstract
An octacosapeptide named pro-somatostatin was isolated from acid extracts of procine hypothalami and had the amino acid sequence .**GRAPHIC**. This octacosapeptide possesses high somatotropin (growth hormone) and prolactin release-inhibiting activity in vitro. It also crossreacts strongly with antisera generated against the somatostain tetradecapeptide. This octacosapeptide is most likely a precursor (pro-hormone) of somatostatin in the hypothalamus. The existence of still larger molecular size precursors of somatostatin was observed.