Regulatory Mechanism of the Cytoplasmic pH by H⁺-Adenosinetriphosphatase

Abstract

Nature prefers simplicity. Streptococcal cytoplasmic pH is regulated in a simple biological manner : change in the amount of the adenosinetriphosphatase (H⁺-ATPase). This enzyme is identical to the F₀F₁-complex of oxidative phosphorylation, which synthesizes adenosinetriphosphate in mitochondria and most of bacteria, whereas it is used as a regulator of the cytoplasmic pH in streptococci which have no respiratory chain. Eukaryotes use the another type of H⁺-ATPase to regulate the internal pH. Thus, the evolutional process of H⁺-ATPase is quite interesting.