Cyclin Pas1/PHO80 Domain Containing Protein 1 (CNPPD1)

Pas1, a G1 cyclin, regulates amino acid uptake and rescues a delay in G1 arrest in Tsc1 and Tsc2 mutants in Schizosaccharomyces pombe. The Rhb1 mutant suppresses amino acid uptake in Deltatsc1 yeast, but not in Deltapas1 yeast. Hence, Pas1 does not regulate amino acid uptake through Rhb1.

In yeast, the repression of acid phosphatase under high phosphate growth conditions requires the trans-acting factor PHO80. The expression of the PHO80 gene, as measured by Northern analysis and level of a PHO80-LacZ fusion protein is independent of the level of phosphate in the growth medium.