PLASMA-MEMBRANE K+/H+-ATPASE FROM LEISHMANIA-DONOVANI

Leishmania donovani has an active K+/H+ exchange system on the surface membrane. Modulation of external K+ concentration resulted in a corresponding change in internal pH (pH(i)) suggesting a link between proton and potassium transport. Although a Na+/H+ antiporter is present on the plasma membrane, its sensitivity to amiloride suggests that it operates independent of K+/H+ exchange. Reduction of cellular ATP with NaN3 and KCN inhibits K+/H+ exchange showing thereby that the process is energy dependent. The K+/H+ exchange is sensitive to inhibitors of the gastric K+/H+-ATPase. It is concluded that the H+-ATPase previously reported on the plasma membrane of L. donovani is in fact a K+/H+-ATPase. (C) 1994 Wiley-Liss, Inc.