Colocalization of WE-14 Immunostaining with the Classical Islet Hormones in the Porcine Pancreas
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WE-14, a tetradecapeptide possessing an N-terminal tryptophanyl (W) and a C-terminal glutamyl (E) residue, was isolated from extracts of a liver metastasis of an ileal carcinoid1 and from a phaeochromocytoma2. Analysis of the chromogranin A (CGA) cDNA sequences revealed that WE-14 represents residues 322–339, 314–331, 341–358, 338–355 and 311–327 of human, bovine, rat, murine and porcine CGA, respectively3. Human and bovine WE-14 are of identical primary structure. The rat and murine peptides are homologous but differ from the human peptide by a single Arg/Lys conservative substitution, whilst, the porcine peptide differs by a single non-conservative Gln/Arg substitution. Each peptide is flanked by conserved pairs of basic amino acid residues. The characterisation of the novel CGA-derived peptides: B-granin4, pancreastatin (PST)5, chromostatin (CST)6, vasostatin7 and parastatin8, in conjunction with the determination of several CGA cDNA sequences which revealed the presence of multiple proteolytic processing sites, supports the concept that CGA is a prohormone.
KeywordsChromaffin Cell Primary Antiserum Porcine Pancreas Basic Amino Acid Residue Identical Primary Structure
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