Binds to the promoters of genes with functions important for the G1/S (start) transition; primarily genes involved in pheromone response, polarized growth and transcription. Regulated in a cell cycle-dependent manner, peaking in G1 phase. Appears exclusively during the G1 and S phases (at protein level). Negatively regulated by transcription factor SBF (SWI4-SWI6 cell-cycle box binding factor). Phosphorylated by CDC28. Present with 284 molecules/cell in log phase SD medium. Belongs to the PLM2/TOS4 family.