Transcription repressor. Component of the regulatory cascade that controls the development of dopaminergic (DA) and serotonergic (5HT) neurons. No expression seen in DA or 5HT neurons. Expressed in the most anterior part of the prospective neural plate along the rostral-caudal axis. At the tail bud stage, expressed in the prospective forebrain region. From 15-somite to 24 hours post-fertilization (hpf), expression is mostly confined to the telencephalon and the anterior-ventral region of diencephalon Expression is restricted to ectoderm at 80% epiboly stage. From 15-somite to 24 hpf, expression is mostly confined to the telencephalon and the anterior-ventral region of diencephalon. In one-eyed pinhead (oep) and cyclops (cyc) mutants, expression in the ventral forebrain was eliminated. Overexpression induced ectopic dlx2 and dlx6 expression. The tof mutant has a reduced number of tyrosine hydroxylase-positive and dopamine beta-hydroxylase-negative DA neurons. Belongs to the krueppel C2H2-type zinc-finger protein family.