1. Enzyme Polymorphism in Rat-Liver Microsomes and Plasma Membranes: 1. An Immunochemical Study of Multienzyme Complexes and other Enzyme-Active Antigens.
- Author
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Blomberg, Fred and Raftell, Marika
- Subjects
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CHROMOSOME polymorphism , *ANTIGENS , *MICROSOMES , *ENZYMES , *IMMUNOELECTROPHORESIS - Abstract
Detergent-soluble antigens from rat liver microsomes and plasma membranes were separated by two-dimensional immunoelectrophoresis. Enzyme activities in the immunoprecipitates were assayed by different staining reactions. Nine different microsomal esterases were detected. Six of these, including one esterase shared with plasma membranes, were inhibited by 0.1 mM difluorophosphate. but not by 1 mM eserine. Plasma membranes and microsomes each contained at least ten nucleoside diphosphatase and triphosphatase-active antigens. Only three precipitates with these activities were detected when plasma membrane extracts were tested against anti-microsomal sera or microsomal extracts against anti-plasma membrane sera. Although the possible immunological identity of these antigens remains to be established these findings suggest that plasma membranes and microsomes have at most three of these nucleoside diphosphatases and triphosphatases in common. Seven microsomal nucleoside diphosphatases and triphosphatases were intimately associated with both acid phosphatase and NADH-neotetrazolium reductase activities. These complexes also contained phospholipids as shown by incorporation experiments either in vivo or in vitro with [14C]-choline or [14C]ethanolamine. Three microsomal UDPase-active antigens did not hydrolyze ATP or ADP and were not associated with acid phosphatase or NADH-neotetrazolium reductase activities. Furthermore, these antigens did not contain any of the labelled phospholipids. Lipid-containing multienzyme complexes of different composition were also detected in the plasma membranes. The nucleoside diphosphatases and triphosphatases in plasma membrane extracts were associated with NADH-neotetrazolium reductase activity and two of them also contained L-leucyl-β-naphthylamidase activity. p-Chloromercuribenzoate (0.1 mM) inhibited all NADH-neotetrazolium reductase activity in the plasma membrane and microsomal precipitates and 10 mM tartrate all acid phosphatase activity in the microsomal precipitates, leaving the other activities intact. This indicated that the various enzyme activities present in the multienzyme complexes depended on separate catalytic sites. The plasma membrane extracts contained three and the microsomal extracts two L-leucyl-β-naphthylamidase-active antigens, respectively. The latter two and one of the plasma membrane antigens were not found to be associated with any other enzyme activities or phospholipids, in contrast to the two plasma membrane antigens mentioned above. [ABSTRACT FROM AUTHOR]
- Published
- 1974
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