Immunoassay of polyphosphatases from different compartments of Saccharomyces cerevisiae yeast cells

Antibodies against purified cell-envelope polyphosphatase of Saccharomyces cerevisiae inhibited the activity both of this and of cytosol polyphosphatases and did not affect the polphosphatases of vacuoles and nuclei isolated from the same yeast. Using immunoblotting, it has been shown that it is the 40-kD polypeptide that binds to these antibodies in preparations of cell-envelope and partially purified cytosol polyphosphatase. The molecular weights of these polypeptides determined by other methods were almost identical. In the vacuolar preparation, the polypeptides of 72 and 40 kD reacted with antibodies, while in the nuclear preparation, those of 64 and 32 kD.