Isolation and structure of a peptide hormone predicted from a mRNA sequence. A second somatostatin from the catfish pancreas.

This laboratory recently observed a cDNA reverse transcript to a specific mRNA from the channel catfish (Ictalurus punctata) pancreas which predicted the presence of a somatostatin gene product different from the previously reported catfish somatostatin (Oyama, H., Bradshaw, R. A., Bates, O. J., and Permutt, A. (1980) J. Biol. Chem. 255, 2251-2254). The gene product was purified using reverse phase high performance liquid chromatography. The peptide was shown to be structurally identical with somatostatin-14 from other species by tryptic mapping, amino acid composition, and sequence. The level of somatostatin-14 in the catfish endocrine pancreas was determined to be 104 micrograms of immunoreactive somatostatin/g of tissue. These observations suggest that the catfish pancreas has at least two structurally distinct somatostatins.