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Na,K-ATPase: radiation inactivation studies.
A A Boldyrev1, O D Lopina, N U Fedosova
1Department of Biochemistry, Moscow State University, U.S.S.R.
Biochemistry International
|January 1, 1990
Summary
Sodium-potassium adenosine triphosphatase (Na,K-ATPase) functions as an oligomeric structure during ATP hydrolysis. Enzyme oligomerization degree increases with membrane lipid microviscosity.
Area of Science:
- Biochemistry
- Membrane protein structure
- Enzyme kinetics
Background:
- Na,K-ATPase is a crucial ion pump involved in maintaining cell potential.
- Understanding its oligomeric state and regulation is vital for cellular function.
Purpose of the Study:
- To investigate the oligomeric structure of Na,K-ATPase using radiation inactivation.
- To correlate enzyme structure with its functional state and lipid environment.
Main Methods:
- Radiation inactivation technique applied to membrane-bound and solubilized Na,K-ATPase.
- Comparison of radiation inactivation size (RIS) with target size (TS) and analytical centrifugation data.
- Enzyme assays using various substrates (ATP, CTP, GTP, p-NPP) in the presence of K+.
Main Results:
- Na,K-ATPase operates as an oligomeric structure during ATP and CTP hydrolysis.
- Oligomerization is dependent on K+ and ATP binding to low-affinity sites.
- Increased membrane lipid microviscosity correlates with a higher degree of enzyme oligomerization.
Conclusions:
- Na,K-ATPase functional state is linked to its oligomeric assembly.
- The lipid environment plays a significant role in modulating Na,K-ATPase oligomerization and function.
- These findings provide insights into the structural dynamics of ion-transporting ATPases.