Transcriptional regulator of the switch between 2 heritable states, the white and opaque states. These 2 cell types differ in many characteristics, including cell structure, mating competence, and virulence. Each state is heritable for many generations, and switching between states occurs stochastically, at low frequency. Contributes to formation of the opaque state, but is not necessary for heritability of the opaque state. Plays a role in cell adhesion and pseudohyphal growth. Involved in acquisition of drug resistance and acts as a repressor of beta-glucan synthesis, thus negatively regulating cell wall integrity. Plays a role in adherence, invasion and damage to oral epithelial cells. Interacts with EFG1. Regulated in response to carbon source, temperature, growth phase, and physical environment. Expression is up-regulated by rapamycine, and thus is under the regulation of the TOR pathway. Binds its own promoter and is also under the control of EFG1.