Expression of the V-ATPase proteolipid subunit of Acetabularia acetabulum in a VMA3-deficient strain of Saccharomyces cerevisiae and study of its complementation

The function of the translation products of six different cDNAs for Acetabu laria V-ATPase proteolipid subunit (AACEVAPD1 to AACEVAPD6) was examined us ing a Saccharomyces cerevisiae VMA3-deficient strain that lacked its own ge ne for one of the proteolipid subunits of V-ATPase. Expression of the cDNAs in the strain revealed that four cDNAs from the six complemented the proto n transport activity into the vacuole, visualized by fluorescence microscop y. The vacuolar-membrane-enriched fractions from the four transformants sho wed crossreactivity with antibodies against the subunits a and A of S. cere visiae V-ATPase. Two translation products from the other two cDNAs were dem onstrated not to be localized in vacuolar membranes, and thus could not com plement the function of the VMA3-deficient strain. As the primary structure s deduced from the former four cDNAs are similar but clearly different from those of the latter two, the latter two translation products may not be ab le to substitute for the VMA3 gene product.