Isolation of [Pro2,Met13]Somatostatin-14 and somatostatin-14 from the frog brain reveals the existence of a somatostatin gene family in a tetrapod

Two somatostatin-related peptides were isolated in pure form from an extract of the brain of the European green frog, Rana ridibunda. The primary structure of the most abundant component was identical to that of mammalian somatostatin-14. The primary structure of the second component, present in approximately 5% of the abundance of somatostatin-14, was established as Ala-Pro-Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Met-Cys. This sequence shows two substitutions (Pro for Gly² and Met for Ser¹³) compared with mammalian somatostatin-14. The data provide evidence for a somatostatin gene family in tetrapods as well as in teleost fish.