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 Possibly exists as a homodimer or a homotrimer. As many as 6 to 8 closely related genes may encode other isoforms of plasma membrane ATPase in tomato, like the LHA1 gene product which is 96% identical to the LHA2 gene product. Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IIIA subfamily.