A novel Cl(-)-pump: intracellular regulation of transport activity

Utilizing a purified basolateral plasma membrane vesicle preparation containing Cl(-)-ATPase, it was demonstrated that ATP, and its subsequent hydrolysis, stimulated both intravesicular Cl- accumulation and intravesicular negativity with almost identical kinetics. Mg2+ also stimulated both pump transport characteristics with an optimal concentration of 3 mM. Similarly, the pH optimum for both pump transport expressions was 7.8. Orthovanadate inhibition of both pump transport characteristics was directly related to its concentration. These results suggested that the active Cl- transport mechanism is electrogenic and is driven by a Cl(-)-stimulated ATPase.