Corepressor targeting diverse transcription regulators. Functions in brown adipose tissue (BAT) differentiation. Isoform 2 probably acts as a scaffold for specialized synapses (By similarity). Interacts with HIPK2, ZNF217 and PNN (By similarity). Interacts with the transcription factors BKLF, delta EF1/AREB6/ZEB, EVI-1 and Friend of GATA (FOG) via the consensus motif P-X-[DNS]-L-[STVA]. 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 (By similarity). Interacts with MCRIP1 (By similarity). Isoform 2 is specifically localized in synaptic ribbon (at protein level). Phosphorylation by HIPK2 on Ser-428 induces proteasomal degradation. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family.