The neurospora plasma membrane ATPase is an electrogenic pump

Abstract

Biochemicalical evidence is presented which demonstrates that the Neurospora crassa plasma membrane ATPase (ATP phosphohydrolase, EC 3.6.1.3) is an electrogenic pump. The electrical potential across the Neurospora plasma membrane, as monitored by [14C]SCN- uptake by isolated Neurospora plasma membrane vesicles, is markedly increased interior positive under conditions of ATP hydrolysis catalyzed by plasma membrane ATPase. [14C]SCN- uptake by the vesicles is minimal in the presence of Tris phosphate, Tris phosphate plus Mg+2, Tris ADP plus Mg+2, and Tris ATP, but is markedly stimulated in the presence of Tris ATP plus Mg+2.