Identification of a 7B2-derived tridecapeptide from bovine adrenal medulla chromaffin vesicles.

1. A novel tridecapeptide was isolated from extracts of bovine adrenal medulla chromaffin vesicles and the primary structure determined to be SVPHFSDEDKDPE. 2. This peptide is identical to the C termini of human and porcine 7B2 and is highly homologous to the same region of the mouse and Xenopus lavis protein. 3. In all these species the homologous peptide is preceded by a pair of lysine residues, a potential proteolytic processing site. 4. Ser6 is part of a well-conserved casein kinase II consensus phosphorylation sequence. Evidence for phosphorylation of this residue was obtained during Edman sequencing. 5. Thus, this novel adrenal medullary probably arises from the posttranslational processing of the bovine 7B2 protein.