Role of transmembrane segment M8 in the biogenesis and function of yeast plasma-membrane H(+)-ATPase.

ABSTRACT: Of the four transmembrane helices (M4, M5, M6, and M8) that pack together to form the ion-binding sites of P(2)-type ATPases, M8 has until now received the least attention. The present study has used alanine-scanning mutagenesis to map structure-function relationships throughout M8 of the yeast plasma-membrane H(+)-ATPase. Mutant forms of the ATPase were expressed in secretory vesicles and at the plasma membrane for measurements of ATP hydrolysis and ATP-dependent H(+) pumping. In secretory vesicles, Ala substitutions at a cluster of four positions near the extracytoplasmic end of M8 led to partial uncoupling of H(+) transport from ATP hydrolysis, while substitution of Ser-800 (close to the middle of M8) by Ala increased the apparent stoichiometry of H(+) transport. A similar increase has

SUBMITTER: Guerra G 

PROVIDER: S-EPMC2267258 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature