Identification of Aly1 and Aly2 as Modulators of Cytoplasmic pH in .

The regulation of intracellular pH in yeast () cells is critical for cell function and viability. In yeast, protons (H) can be excreted from the cell by plasma membrane ATPase PMA1 and pumped into vacuoles by vacuolar H-ATPase. Because PMA1 is critical to the survival of yeast cells, it is unknown whether other compensatory components are involved in pH homeostasis in the absence of PMA1. To elucidate how intracellular pH is regulated independently of PMA1, we employed a screening approach by exposing the yeast haploid deletion mutant library (ver 4.0) to the selective plant plasma membrane H-ATPase inhibitor PS-1, which we previously reported. After repeated screenings and verification, we identified two proteins, and , that play a role in the regulation of intracellular pH when PMA1 is deficient. Our research uncovers a new perspective on the regulation of intracellular pH related to PMA1 and also preliminarily reveals a role for and in the regulation of intracellular pH.