Egasyn, a protein which determines the subcellular distribution of beta-glucuronidase, has esterase activity.
The glycoprotein egasyn complexes with and stabilizes precursor beta-glucuronidase in microsomes of several mouse organs. Several observations indicate egasyn is, in addition, an esterase. Liver homogenates of egasyn-positive strains have specific electrophoretically separable esterases which are absent in egasyn-negative mice. These esterases react with anti-egasyn serum. A specific esterase was likewise complexed with immunopurified microsomal beta-glucuronidase. The esterases were, like egasyn and microsomal beta-glucuronidase, concentrated in the microsomal subcellular fraction. Egasyn which is not bound to beta-glucuronidase, which represents 80-90% of total liver egasyn, is not complexed with other liver proteins. Egasyn, therefore, specifically stabilizes beta-glucuronidase in microsomes. The esterase activity is inhibited by bis-p-nitrophenyl phosphate indicating it is a carboxyl esterase. Several possible functions of egasyn-esterase activity are discussed.
D000818:Animals; D002265:Carboxylic Ester Hydrolases; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D004950:Esterases / Q000378:metabolism*; D005966:Glucuronidase / Q000378:metabolism*; D007106:Immune Sera; D008099:Liver / Q000166:cytology / Q000201:enzymology; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013347:Subcellular Fractions / Q000201:enzymology; D014018:Tissue Distribution
D007106:Immune Sera; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D004950:Esterases; D002265:Carboxylic Ester Hydrolases; C009751:egasyn; D005966:Glucuronidase