Corepressor targeting diverse transcription regulators such as GLIS2 or BCL6. Has dehydrogenase activity. Involved in controlling the equilibrium between tubular and stacked structures in the Golgi complex. Functions in brown adipose tissue (BAT) differentiation. Cofactor binding induces a conformational change. Homo- or heterodimer. Heterodimer with CTBP2. Interacts with ELK3 (via its PXDLS motif). Interacts with RBBP8 (via its PXDLS motif). Interacts with PNN, MECOM and ZFHX1B. Interacts with ZNF366 (via PXDLS motif) (By similarity). Interaction with SATB1 (non-acetylated form); the interaction stabilizes its attachment to DNA and promotes transcription repression. Interacts with PRDM16; the interaction represses white adipose tissue (WAT)-specific genes expression. Interacts with GLIS2, HIPK2, FOXP1, FOXP2, HDAC4, HDAC5, HDAC9, NRIP1, WIZ and ZNF217. Interacts with BCL6; the interaction is required for BCL6 transcriptional autoinhibition and inhibition of some BCL6 target genes. Interacts with IKZF4. Interacts with MCRIP1 (unphosphorylated form, via the PXDLS motif); competitively inhibiting CTBP-ZEB1 interaction (By similarity). Interacts with Bassoon/BSN; this interaction targets and anchors CTBP1 to presynapses (By similarity). Interacts with SIMC1 (By similarity). Expressed in a wide range of adult tissues. Expressed throughout the developmental stages. ADP-ribosylated; when cells are exposed to brefeldin A. The level of phosphorylation appears to be regulated during the cell cycle. Phosphorylation by HIPK2 on Ser-423 induces proteasomal degradation (By similarity). Sumoylation on Lys-429 is promoted by the E3 SUMO-protein ligase CBX4. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family. Truncated N-terminus.