REG1 binds to protein phosphatase type 1 and regulates glucose repression in Saccharomyces cerevisiae.
Protein phosphatase type 1 (PP1) is encoded by GLC7, an essential gene in Saccharomyces cerevisiae. The GLC7 phosphatase is required for glucose repression and appears to function antagonistically to the SNF1 protein kinase. Previously, we characterized a mutation, glc7-T152K, that relieves glucose repression but does not interfere with the function of GLC7 in glycogen metabolism. We proposed that the mutant GLC7T152K phosphatase is defective in its interaction with a regulatory subunit that directs participation of PP1 in the glucose repression mechanism. Here, we present evidence that REG1, a protein required for glucose repression, is one such regulatory subunit. We show that REG1 is physically associated with GLC7. REG1 interacts with GLC7 strongly and specifically in the two-hybrid system, and REG1 and GLC7 fusion proteins co-immunoprecipitate from cell extracts. Moreover, overexpression of a REG1 fusion protein suppresses the glc7-T152K mutant defect in glucose repression. This and other genetic evidence indicate that the two proteins function together in regulating glucose repression. These results suggest that REG1 is a regulatory subunit of PP1 that targets its activity to proteins in the glucose repression regulatory pathway.
Tu
J
J
Integrated Program in Cellular Biology, Molecular Biology and Biophysics Studies, Columbia University, New York, NY 10032, USA.
Carlson
M
M
D001483:Base Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D015151:Immunoblotting; D008969:Molecular Sequence Data; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011233:Precipitin Tests; D054645:Protein Phosphatase 1; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins
D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D006003:Glycogen; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; C070829:REG1 protein, S cerevisiae; D005947:Glucose