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 ab...

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Bibliographic Details
Published in:The Journal of biological chemistry 1985-12, Vol.260 (29), p.15802-15808
Main Authors: Medda, S, Swank, R T
Format: Article
Language:English
Subjects:
Animals
Carboxylic Ester Hydrolases
Cross Reactions
Electrophoresis, Polyacrylamide Gel
Esterases - metabolism
Glucuronidase - metabolism
Immune Sera
Liver - cytology
Liver - enzymology
Membrane Glycoproteins
Membrane Proteins - metabolism
Mice
Mice, Inbred BALB C
Mice, Inbred C57BL
Subcellular Fractions - enzymology
Tissue Distribution
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Summary: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.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(17)36329-9