Corepressor targeting diverse transcription regulators. Isoform 2 probably acts as a scaffold for specialized synapses (By similarity). Functions in brown adipose tissue (BAT) differentiation. Interacts with HIPK2 and PNN (By similarity). Interacts with the transcription factors ZNF217, BKLF, delta EF1/AREB6/ZEB, EVI-1 and Friend of GATA (FOG) via the consensus motif P-X-[DNS]-L-[STVA]. Interacts also with the C-terminus of adenovirus E1A protein. Can form a complex with BKLF on a CACCC-box oligonucleotide. Can form homodimers or heterodimers of CTBP1 and CTBP2. Interacts with NRIP1 and WIZ. Interacts with PRDM16; represses white adipose tissue (WAT)-specific genes expression. Interacts with MCRIP1 (By similarity). Found in all tissues except spleen and liver. Strong expression confined to the embryonic stages. Phosphorylation by HIPK2 on Ser-428 induces proteasomal degradation. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family.