A NOVEL CL--PUMP - INTRACELLULAR REGULATION OF TRANSPORT ACTIVITY

Utilizing a purified basolateral plasma membrane vesicle preparation c ontaining Cl--ATPase, it was demonstrated that ATP, and its subsequent hydrolysis, stimulated both intravesicular Cl- accumulation and intra vesicular negativity with almost identical kinetics. Mg2+ also stimula ted 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 characterist ics 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. (C) 1995 Academic Press, Inc.