Characterization of immunoreactive pancreastatin in porcine tissues

Pancreastatin is a 49 amino acid peptide with a C-terminal glycine amide originally isolated from porcine pancreas. There are strong indications that pancreastatin is derived from chromogranin A, since the amino acid sequence 240-288 in porcine chromogranin A contains pancreastatin flanked by typical signals for proteolytic processing. In the present study the distribution and molecular nature of immunoreactive pancreastatin were examined in selected porcine tissues. For this purpose a radioimmunoassay specific for the C-terminal sequence of porcine pancreastatin, that did not cross-react with porcine chromogranin A was used in combination with gel permeation chromatography and reverse-phase high-pressure liquid chromatography (HPLC). We demonstrated the presence of pancreastatin, a C-terminal pancreastatin fragment and N-terminally extended molecular forms in the examined tissues. Pancreastatin predominated in the pancreas and stomach antrum, while N-terminally extended molecular forms were mainly present in the stomach body, jejunum and adrenal gland. The specific distribution pattern of the molecular forms probably reflects a tissue-specific processing of chromogranin A.