Yeast plasma membrane ATPase is essential for growth and has homology with (Na⁺ + K⁺), K⁺- and Ca²⁺-ATPases

Abstract

The plasma membrane ATPase of plants and fungi is a hydrogen ion pump¹. The proton gradient generated by the enzyme drives the active transport of nutrients by H⁺-symport. In addition, the external acidification in plants and the internal alkalinization in fungi, both resulting from activation of the H⁺ pump, have been proposed to mediate growth responses. This ATPase has a relative molecular mass (Mr) similar to those of the Na⁺-, K⁺- and Ca²⁺-ATPases of animal cells and, like these proteins, forms an aspartylphosphate intermediate. We have cloned, mapped and sequenced the gene encoding the yeast plasma membrane ATPase (PMA1) and report here that it maps to chromosome VII adjacent to LEU1. The strong homology between the ammo-acid sequence encoded by PMA1 and those of (Na⁺ + K⁺), Na⁺-, K⁺- and Ca²⁺-ATPases is consistent with the notion that the family of cation pumps which form a phosphorylated intermediate evolved from a common ancestral ATPase. The function of the PMA1 gene is essential because a null mutation is lethal in haploid cells.