Cyclin-dependent kinase (CDK) inhibitor; regulates Pho80p-Pho85p and Pcl7p-Pho85p cyclin-CDK complexes in response to phosphate levels; inhibitory activity for Pho80p-Pho85p requires myo-D-inositol heptakisphosphate (IP7) generated by Vip1p; senses phosphate metabolites via the SPX domain to regulate pexophagy in response to phosphate starvation; relative distribution to the nucleus increases upon DNA replication stress