Rate limitation of (Na+ + K+)-stimulated adenosinetriphosphatase by membrane acyl chain ordering.
- 1 October 1979
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 76 (10) , 4893-4897
- https://doi.org/10.1073/pnas.76.10.4893
Abstract
A somatic cell mutant (CR1) of the Chinese hamster ovary cell line (CHOK1) that is defective in the regulation of cholesterol biosynthesis can be grown under conditions in which plasma membranes from these cells display various cholesterol contents and acyl chain order parameters. The (Na+ + K+)-stimulated ATPase (ATP phosphohydrolase, EC 3.6.1.3) from these cells varied in activity by a factor of 10 as the order parameter was varied, and the activity exhibited an exponential dependence on this parameter. Under these conditions the number of Na+,K+-ATPase molecules remained constant by affinity labeling with [.gamma.-32P]ATP in the absence of Na+. Control experiments showed that alteration in cholesterol content without change in order parameter did not result in altered enzyme activity. Under these conditions, the rate of catalysis by the Na+,K+-ATPase is determined by the order parameter. These studies suggest a physical mechanism by which variation of membrane lipid composition or other factors that determine membrane lipid acyl chain order parameter can result in variation in membrane enzyme activity.This publication has 17 references indexed in Scilit:
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