SON1P IS A COMPONENT OF THE 26S PROTEASOME OF THE YEAST SACCHAROMYCES-CEREVISIAE

A son1 mutant was isolated as a mutant showing synthetic lethality wit h nin1-1 which is defective in the p31 component of the regulatory sub unit of the yeast 26S proteasome, son1 Delta showed a synthetic effect with sen3 Delta and sun1 Delta, both components of the 26S proteasome , and with cdc28-1N. The 26S proteasome was partially purified from th e wild type yeast, The FPLC fractions were analyzed by Western blottin g using anti-Son1p antibody and antibodies against some authentic subu nits of the 26S proteasome, and we found that Son1p comigrated with co mponents of the 26S proteasome, The 26S proteasome containing fraction was immunoprecipitated with anti-Son1p antibody, The resultant precip itate contained Nin1p, Sun1p, TBP1, and the 20S proteasome. Combining genetic and biochemical results together, we concluded that Son1p is a component of the yeast 26S proteasome. (C) 1998 Federation of Europea n Biochemical Societies.