Several compartments of Saccharomyces cerevisiae are equipped with Ca(2+)-ATPase(s)

Sucrose density fractionation of yeast membranes revealed two major and two minor peaks of 45Ca2+ transport activity which all co-migrate with marker enzymes of the endoplasmic reticulum, Golgi and membranes associated with these compartments as well as with ATPase activity measured when all other known ATPase are inhibited. Co-migration of 45Ca2+ transport and ATPase activities was also found after removal of plasma membranes by concanavalin A treatment. SDS-PAGE at pH 6.3 shows the Ca(2+)-dependent formation of acyl phosphate polypeptides of about 110 and 200 kDa. It is concluded that several compartments or sub-compartments of yeast are equipped with Ca(2+)-ATPase(s). It is proposed that these compartments are derived from the protein secretory apparatus of yeast.