FIG. 1.

Immunoprecipitates of full-length Gal4p show reduced levels of Gal80p in the presence of Gal3p, galactose, and ATP. Protein extracts were prepared from Gly-Lac-grown cultures of yeast strain Sc338 carrying either plasmid pMEGA3 (GAL4⁹⁰¹ GAL80 GAL3) or plasmid pMEGA3-Δ3 (GAL4⁹⁰¹ GAL80). The anti-901 monoclonal antibody was used to immunoprecipitate 901-tagged Gal4p from yeast extracts comprising 3 mg of proteins. Immunoprecipitations were carried out in the absence (lane 1) and presence (lane 2) of galactose and ATP. Precipitated proteins were analyzed by Western immunoblotting. Gal4p and Gal80p were detected on the same blot by using a combination of rabbit polyclonal anti-Gal4p and anti-Gal80p. (A) Immunoprecipitations were performed on extracts of Sc338 carrying pMEGA3. Due to markedly different intensities of immunologically detected Gal4p⁹⁰¹ and Gal80p bands, two different chemiluminescence film exposures (A1 and A2) of the same immunoblot are shown. wt, wild type. (B) Immunoprecipitations were performed on extracts of Sc338 carrying pMEGA3-Δ3.