The plasma membrane ATPase of plants and fungi is a hydrogen ion pump. The proton gradient it generates drives the active transport of nutrients by H(+)-symport. The resulting external acidification and/or internal alkinization may mediate growth responses. ATP + H(+)(in) + H2O = ADP + 2 H(+)(out) + phosphate Expressed at high levels in root, stem, leaf and flower. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IIIA subfamily.