FAR1 AND THE G(1) PHASE SPECIFICITY OF CELL-CYCLE ARREST BY MATING FACTOR IN SACCHAROMYCES-CEREVISIAE

Significant accumulation of Far1p is restricted to the G(1) phase of the Saccharomyces cerevisiae cell cycle, Here we demonstrate yeast cell cycle regulation of Far1p proteolysis, Deletions within the 50 N-terminal amino acids of Far1p increase stability and reduce cell cycle regulation of Far1p abundance, Whereas wild-type Far1p specifically and exclusively promotes G(1) phase arrest in response to mating factor, stabilized Far1p promoted arrest both during and after G(1). The loss of the G(1) specificity of Far1p action requires elimination of FAR1 transcriptional regulation (by means of the GAL1 promoter) as well as N-terminal truncation, Thus, the cell cycle specificity of mating factor arrest may be largely due to cell cycle regulation of FAR1 transcription and protein stability.