title: Regulated secretory proteins in the exocrine pancreas aggregate under conditions that mimic the trans-Golgi network.
abstract: Fifteen pancreatic secretory proteins, including seven serine-endoproteinases (isoenzyme forms of trypsinogen, chymotrypsinogen and proelastase), four metallo-exoproteinases (isoenzymic forms of procarboxypeptidase A and procarboxypeptidase B), amylase, lipase, and two forms of carboxyl ester lipase were observed to aggregate under conditions of acidic pH (5.5) and calcium that mimic the trans-Golgi network. Subsequent neutralization of the pH resulted in disruption of protein aggregates and solubilization of pancreatic (pro)enzymes. In the absence of secretory granule membranes, granule contents display an "intrinsic" property for reversible, pH-dependent aggregation under conditions of mild acidification.
authors.affiliation: Laboratory of Cell and Molecular Biology, Charles A. Dana Research Institute, Thorndike Laboratory, Boston, MA.
authors.forename: S D
authors.initials: SD
authors.lastname: Freedman
authors.forename: G A
authors.initials: GA
authors.lastname: Scheele
mesh_terms: D000681:Amylases / Q000302:isolation & purification / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000201:enzymology*; D004285:Dogs; D010450:Endopeptidases / Q000302:isolation & purification / Q000378:metabolism*; D004792:Enzyme Precursors / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D005260:Female; D006056:Golgi Apparatus / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000302:isolation & purification / Q000378:metabolism*; D046911:Macromolecular Substances; D010179:Pancreas / Q000201:enzymology*
chemical_list: D004792:Enzyme Precursors; D046911:Macromolecular Substances; D008049:Lipase; D000681:Amylases; D010450:Endopeptidases; D002118:Calcium