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Endogenous K+/H+ exchange activity in the Sf9 insect cell line
V Vachon1, M J Paradis, M Marsolais
1Groupe de recherche en transport membranaire, Université de Montréal, Quebec, Canada.
Biochemistry
|November 21, 1995
Summary
Sf9 cells utilize a potassium/hydrogen antiporter to regulate intracellular pH. This K+/H+ antiporter is crucial for proton movement across the cell membrane, influencing cell pH dynamics.
Area of Science:
- Cell biology
- Biochemistry
- Physiology
Background:
- Intracellular pH (pHi) regulation is vital for cellular function.
- Sf9 cells are a common model system in biological research.
Purpose of the Study:
- To investigate the role of extracellular medium composition on Sf9 cell intracellular pH.
- To identify the mechanisms governing proton transport across the Sf9 cell membrane.
Main Methods:
- Utilized the fluorescent pH indicator 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) for real-time pHi measurements.
- Manipulated extracellular ion concentrations (K+, Li+, Na+, Rb+, Cs+) and pH to observe effects on pHi.
- Assessed cellular buffer capacity as a function of pHi.
Main Results:
- Resting pHi of Sf9 cells was slightly lower than extracellular pH.
- Extracellular potassium (K+) significantly influenced pHi, with K+ removal causing rapid acidification.
- A K+/H+ antiporter was identified as the primary mechanism for K+-dependent H+ efflux, with a Km of approximately 12 mM.
Conclusions:
- A K+/H+ antiporter is essential for regulating proton movement across the Sf9 cell membrane.
- This antiporter plays a key role in maintaining cellular pH homeostasis in response to external K+ levels.