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Plasma membrane K+/H(+)-ATPase from Leishmania donovani
S Jiang1, S A Anderson, G D Winget
1Department of Biological Sciences, University of Cincinnati, Ohio 45221.
Journal of Cellular Physiology
|April 1, 1994
Summary
Leishmania donovani utilizes a K+/H+ exchange system for proton and potassium transport, which is energy-dependent. This process is sensitive to gastric K+/H(+)-ATPase inhibitors, indicating it
Area of Science:
- Cellular biology
- Parasitology
- Biochemistry
Background:
- Leishmania donovani possesses a surface membrane with transport systems influencing internal pH.
- Previous research suggested the presence of a proton pump on the plasma membrane.
Purpose of the Study:
- To investigate the nature of the K+/H+ exchange system in Leishmania donovani.
- To determine the relationship between potassium transport and internal pH regulation.
- To identify the specific type of ATPase involved in proton and potassium transport.
Main Methods:
- Modulation of external potassium (K+) concentration.
- Measurement of internal pH (pHi).
- Inhibition studies using amiloride, NaN3, KCN, and gastric K+/H(+)-ATPase inhibitors.
Main Results:
- External K+ concentration changes correlated with internal pH (pHi) shifts, suggesting coupled transport.
- A Na+/H+ antiporter was identified but operates independently of K+/H+ exchange.
- Inhibition of cellular ATP synthesis (using NaN3 and KCN) reduced K+/H+ exchange activity, confirming energy dependence.
- K+/H+ exchange was sensitive to inhibitors of gastric K+/H(+)-ATPase.
Conclusions:
- The K+/H+ exchange system in Leishmania donovani is energy-dependent.
- The previously identified H+-ATPase on the plasma membrane is, in fact, a K+/H(+)-ATPase.
- This finding clarifies the mechanism of ion transport and pH regulation in Leishmania donovani.