Transcriptional repressor that negatively regulates G1-specific, SBF- and MBF-dependent transcription. Binds via SBF to promoters of G1-specific genes to repress transcription in early G1. During G1, phosphorylated by cyclin-CDK CLN3-CDC28 and progressively hyperphosphorylated by CDK associated with other G1-cyclins, which leads to dissociation of WHI5 from SBF, activating SBF-dependent transcription in late G1. Elimination of CDK activity at the end of mitosis by the mitotic exit network (MEN) allows WHI5 to reassociate with SBF to again repress G1/S transcription. Interacts with the heterodimeric transcription factors SBF (SWI4-SWI6 cell-cycle box binding factor) and MBF (MluI cell-cycle box binding factor), each composed of the transcriptional coactivator SWI6 and a sequence-specific DNA-binding protein SWI4 or MBP1, respectively. Shuttles in a cell cycle-regulated manner. Localizes to the nucleus, where it is associated with SBF-dependent promoters. In late G1 phase, phosphorylation by G1-specific cyclin-CDK causes its export to the cytoplasm. Elimination of CDK activity at the end of mitosis allows WHI5 to reenter the nucleus. By transcription factor HCM1 during S phase. Phosphorylation by the cyclin-dependent kinase (CDK) CDC28 controls both subcellular location and association of WHI5 with SBF. Present with 1440 molecules/cell in log phase SD medium. Belongs to the WHI5/NRM1 family.