Phosphorylation of the transcription factor PHO4 by a cyclin-CDK complex, PHO80-PHO85

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Science  25 Feb 1994:
Vol. 263, Issue 5150, pp. 1153-1156
DOI: 10.1126/science.8108735


Induction of the yeast gene PHO5 is mediated by the transcription factors PHO2 and PHO4. PHO5 transcription is not detectable in high phosphate; it is thought that the negative regulators PHO80 and PHO85 inactivate PHO2 and PHO4. Here it is reported that PHO80 has homology to yeast cyclins and interacts with PHO85, a p34cdc2/CDC28-related protein kinase. The PHO80-PHO85 complex phosphorylates PHO4; this phosphorylation is correlated with negative regulation of PHO5. These results demonstrate the existence of a cyclin-cdk complex that is used for a regulatory process other than cell-cycle control and identify a physiologically relevant substrate for this complex.

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