Large variations in the proteolytic formation of a chromogranin A-derived peptide (GE-25) in neuroendocrine tissues.

摘要: We have established a radioimmunoassay for GE-25, peptide present in the C-terminal end of primary amino acid sequence chromogranin A where it is flanked by typical proteolytic cleavage sites. Gel-filtration HPLC was used to characterize molecular sizes immunoreactive molecules. The antiserum recognized not only free but also larger precursors including proprotein A. tissues with highest levels GE-25 immunoreactivity were decreasing order: adrenal medulla, three lobes pituitary gland, intestinal mucosa, pancreas and various brain regions. In medulla parathyroid gland most found be as intact some intermediate-sized peptides, without significant amounts peptide. anterior pituitary, even more so intestine, shift smaller peptides seen. posterior intermediate predominant material apparently represented GE-25. reverse-phase chromatography this eluted exactly like synthetic standard, which allows tentative identification tissue processing intermediate, corresponding well precursor proteins being present. suggest that those organs (endocrine pancreas, pituitary) major hormones are proteolytically processed there concomitant proteolysis further susceptible peptides. Since formed vivo conserved between species seems good candidate having specific physiological functions.