Two forms of yeast plasma membrane H+-ATPase:: Comparison of yield and effects of inhibitors

Classical isolation procedure for plasma membrane H+-ATPase of Saccharomyces cerevisiae based on fractional centrifugation yielded always a roughly two-fold greater amount of membranes when starting from glucitol-preincubated than from glucose-preincubated yeast. This difference persisted all the way to thr purified plasma membranes and to the purified H+-ATPase The ATP-hydrolyzing activity by plasma membranes was roughly twice greater in glucose-preincubated cells than in the D-glucitol-preincubated ones while the purified enzyme was 7 times more active after glucose than after glucitol Effects of diethylstilbestrol. suloctidil, erythrosin B, vanadate and dicarbanonaboranuide were ver), similar on plasma membrane-localized and purified ATPases or both Forms, suggesting that both preparations contain the two ATPase forms. the glucose-preincubated one being richer in the activated Form while the glucitol-preincubated one contains less of it.