Characterization of three peptides derived from prosomatostatin [prosomatostatin-(1-63)-, -(65-76)- and -(79-92)-peptides] in a human pancreatic tumour.
By using only reverse-phase h.p.l.c., three fragments of prosomatostatin were isolated from an extract of a human pancreatic neuroendocrine tumour that produced somatostatin, vasoactive intestinal polypeptide and gastrin-releasing peptide. The amino acid composition of the peptides indicated that they represented prosomatostatin-(1-63)-peptide, prosomatostain-(65-76)-peptide and prosomatostatin-(79-92)-peptide (somatostatin-14). The identity of prosomatostatin-(1-63)-peptide was confirmed by characterization of the products of digestion with Armillaria mellea (honey fungus) proteinase. Partial micro-sequencing of prosomatostatin-(1-63)-peptide showed that the Gly24-Ala25 bond of preprosomatostatin was the site of cleavage of the signal peptide. Thus human prosomatostatin is a protein of 92 amino acid residues that is proteolytically cleaved in a pancreatic tumour at the site of a dibasic-residue (arginine-lysine) processing site and at a single-monobasic-residue (arginine) processing site.
D000596:Amino Acids / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D010450:Endopeptidases; D006801:Humans; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis* / Q000302:isolation & purification; D011498:Protein Precursors; D013004:Somatostatin
D000596:Amino Acids; D010446:Peptide Fragments; D011498:Protein Precursors; D013004:Somatostatin; C028456:prosomatostatin; D010450:Endopeptidases; C028084:Armillaria mellea neutral proteinase