The yeast Pho80-Pho85 cyclin-CDK complex has multiple substrates.
The Pho85-Pho80 cyclin-CDK (cyclin-dependent protein kinase) complex of Saccharomyces cerevisiae functions as a key regulator of the phosphate-repressible acid phosphatase system. We have further characterized the Pho85-Pho80 kinase complex and identified the Pho80 cyclin subunit and the Pho81 CDK inhibitor as substrates of the Pho85 protein kinase. The phosphorylation sites within Pho80 have been identified at Ser234 and Ser267. Of the two sites, phosphorylation of Ser234 is required for Pho80 function, to form an active kinase complex and repress acid phosphatase expression. Evidence suggests that the activity of Pho81 is regulated by a post-translational modification and therefore that Pho85-mediated phosphorylation of Pho81 may alter its ability to function as a CDK inhibitor. Thus, the control of acid phosphatase expression involves the phosphorylation of several of the regulatory components of the system.
Waters
Norman C
NC
Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA.
Knight
Janine P
JP
Creasy
Caretha L
CL
Bergman
Lawrence W
LW
D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D047468:Immunoprecipitation; D008970:Molecular Weight; D010766:Phosphorylation; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism
D016213:Cyclins; D004268:DNA-Binding Proteins; C060292:PHO4 protein, S cerevisiae; C066824:PHO80 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D018844:Cyclin-Dependent Kinases; C058605:PHO85 protein, S cerevisiae