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 corre sponding change in internal pH (pH(i)) suggesting a link between proto n and potassium transport. Although a Na+/H+ antiporter is present on the plasma membrane, its sensitivity to amiloride suggests that it ope rates independent of K+/H+ exchange. Reduction of cellular ATP with Na N3 and KCN inhibits K+/H+ exchange showing thereby that the process is energy dependent. The K+/H+ exchange is sensitive to inhibitors of th e 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+-ATPa se. (C) 1994 Wiley-Liss, Inc.