Transcription factor required for the efficient replication of minichromosomes and the transcriptional regulation of early cell cycle genes. Activates transcription of ECB-dependent genes during the G1/M phase. Genes that contain a ECB (early cell box) element in their transcription regulatory region are transcribed only during G1/M phases. Interacts with the alpha-2 repressor or with the alpha-1 activator thereby regulating the expression of mating-type-specific genes. With ARG80, ARG81 and ARG82, coordinates the expression of arginine anabolic and catabolic genes in response to arginine. Homodimer. Binds DNA with a high specificity in complex with mating-type protein ALPHA1. Also binds DNA with a high specificity as a heterotetramer consisting of an ALPHA2 dimer and an MCM1 dimer. Interacts with YHP1 and YOX1, possibly leading to its inactivation. Interacts with ARG80 and ARG82. Present with 8970 molecules/cell in log phase SD medium.