Master transcription factor that controls the differentiation of acute-stage tachyzoite parasites into chronic-stage bradyzoites, which form intracellular cysts resistant to immune clearance and existing therapies (PubMed:31955846). Sufficient to drive differentiation into bradyzoite stage (PubMed:31955846). Following translation in response to stress conditions, binds to the promoter of many chronic stage-specific genes and promotes their expression, thereby driving differentiation into bradyzoites (PubMed:31955846). Expressed at a similar level during both the chronic and acute stages of infection (PubMed:31955846). However, transcripts are only translated during the chronic stage of infection, in response to stress conditions (PubMed:31955846). Regulated at the translation level: while it is expressed during both the chronic and acute stages of infection, transcripts are only translated during the chronic stage of infection. Parasites grow normally under standard conditions but fail to differentiate into chronic-stage bradyzoites under all induction conditions tested (PubMed:31955846). Parasites are unable to form brain cysts in mice (PubMed:31955846).