Structure and Assembly of the Yeast V-ATPase.

The yeast V-ATPase belongs to a family of V-type ATPases present in all eucaryotic organisms. In Saccharomyces cerevisiae the V-ATPase is localized to the membrane of the vacuole as well as the Golgi complex and endosomes. The V-ATPase brings about the acidification of these organelles by the transport of protons coupled to the hydrolysis of ATP. In yeast, the V-ATPase is composed of 13 subunits consisting of a catalytic V[SUB1] domain of peripherally associated proteins and a protontranslocating V[SUB0] domain of integral membrane proteins. The regulatory subunit, Vmal3p, was the first V-ATPase subunit to have its crystal structure determined. In addition to proteins forming the functional V-ATPase complex, three ER-localized proteins facilitate the assembly of the V[SUB0] subunits following their translation and insertion into the membrane of the ER. Homologues of the Vma21p assembly factor have been identified in many higher eukaryotes supporting a ubiquitous assembly pathway for this important enzyme complex. [ABSTRACT FROM AUTHOR]