Involvement of the esterase active site of egasyn in compartmentalization of beta-glucuronidase within the endoplasmic reticulum.
Organophosphorous compounds, which are potent inhibitors of egasyn-esterase activity, caused a rapid dissociation of the high molecular weight egasyn-microsomal beta-glucuronidase complex when administered in vivo or when added in vitro to microsomal suspensions. The dissociation was relatively specific to phosphodiester inhibitors of the esterase active site. Also, the egasyn-esterase active site was inaccessible to substrates and to inhibitors when egasyn was complexed to beta-glucuronidase. Dissociation of the egasyn-microsomal beta-glucuronidase complex in vivo by organophosphorous compounds was followed by massive and rapid secretion of microsomal beta-glucuronidase, but not egasyn, into plasma. These experiments implicate the egasyn-esterase active site in attachment of microsomal beta-glucuronidase to egasyn by a novel mechanism that, in turn, compartmentalizes beta-glucuronidase within the endoplasmic reticulum.
D000818:Animals; D001665:Binding Sites; D002265:Carboxylic Ester Hydrolases; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000648:ultrastructure; D004950:Esterases; D005966:Glucuronidase / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology* / Q000648:ultrastructure; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D008954:Models, Biological; D051381:Rats; D011919:Rats, Inbred Strains
D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D004950:Esterases; D002265:Carboxylic Ester Hydrolases; C009751:egasyn; D005966:Glucuronidase