Transcriptional repressor required to restrict transcription of ECB-dependent genes to the G1/M phase by repressing their transcription during the interval from late G1 to M phases. Genes that contain a ECB (early cell box) element in their transcription regulatory region are transcribed only during G1/M phases. In vitro, is capable of binding to the DNA of the leucine tRNA gene. Interacts with MCM1. Expressed from late G1 phase. Transcriptionally activated by SWI4-SWI6 heterodimer. Present with 861 molecules/cell in log phase SD medium.