title: Characterization of a processing protease that converts the precursor form of gamma-glutamyltranspeptidase to its subunits.
abstract: Previously it was found that the proteolytic processing of precursors of gamma-glutamyltranspeptidase takes place on the brush border membrane of the kidney. The activity of the processing protease in purified brush border membranes was examined using endogenous substrates labeled with [3H]fucose and [35S]methionine. On incubation with brush border membranes in vitro, the precursors were converted stoichiometrically to two subunits, and the reaction followed first order kinetics with a rate constant k of -0.048 min-1. The enzyme responsible for this conversion was membrane-bound, had a weakly basic optimum pH and was inhibited by serine protease inhibitors. These results suggest that the precursor of gamma-glutamyltranspeptidase is processed to the mature form by a serine protease bound to the brush border membrane of kidney.
mesh_terms: D000818:Animals; D004789:Enzyme Activation; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000201:enzymology*; D007700:Kinetics; D046911:Macromolecular Substances; D008871:Microvilli / Q000201:enzymology; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
chemical_list: D046911:Macromolecular Substances; D011480:Protease Inhibitors; D005723:gamma-Glutamyltransferase; D010447:Peptide Hydrolases