Transcription factor that binds specifically to the DRE (dual repressor element) and represses HTR1A gene transcription in neuronal cells. The combination of calcium and ATP specifically inactivates the binding with FRE. May play a role in the altered regulation of HTR1A associated with anxiety and major depression. Mediates HDAC-independent repression of HTR1A promoter in neuronal cell. Performs essential function in controlling functional maturation of synapses. Highly expressed in brain, expression is enriched in the gray matter and strongest in the olfactory bulb. Expressed at 12 dpc throughout the ventricular zone and developing cortical plate and ganglionic eminences. At 16 dpc detected throughout the brain but most strongly in the cortical plate. At postnatal day 3 expressed widely with strong expression in cerebral cortex and hippocampus. The C2 domain is required for the repression. Knockout mice die soon after birth, apparently because of their inability to breathe. Belongs to the CC2D1 family.