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. NAD is required for efficient interaction with E1A. Cofactor binding induces a conformation change. Homo- or heterodimer. Heterodimer with CTBP2. Interacts with PRDM16; the interaction represses white adipose tissue (WAT)-specific genes expression. Interacts with GLIS2, FOXP2, HDAC4, HDAC5, HDAC9 and ZNF217. Interacts with ELK3 (via its PXDLS motif). Interacts with RBBP8 (via its PXDLS motif); the interaction is disrupted by binding to adenovirus E1A. Interacts with FOXP1, HIPK2, PNN, NRIP1, MECOM, ZFHX1B and WIZ. Interacts with ZNF366 (via PXDLS motif) (PubMed:16393996, PubMed:17085477). Interaction with SATB1 (non-acetylated form); the interaction stabilizes its attachment to DNA and promotes transcription repression. Interacts with BCL6; the interaction is required for BCL6 transcriptional autoinhibition and inhibition of some BCL6 target genes. Interacts with IKZF4 (By similarity). Interacts with MCRIP1 (unphosphorylated form, via the PXDLS motif); competitively inhibiting CTBP-ZEB1 interaction (PubMed:25728771). Interacts with Bassoon/BSN; this interaction targets and anchors CTBP1 to presynapses (By similarity). Interacts with SIMC1 (PubMed:23707407). (Microbial infection) Interacts with Epstein-Barr virus EBNA3 and EBNA6. (Microbial infection) Interacts with adenovirus E1A protein (via its C-terminus); the interaction disrupts the interaction of CTBP1 with RBBP8. (Microbial infection) Interacts with human adenovirus 5 E1A protein; this interaction seems to potentiate viral replication. Expressed in germinal center B-cells. The level of phosphorylation appears to be regulated during the cell cycle. Phosphorylation by HIPK2 on Ser-422 induces proteasomal degradation. ADP-ribosylated; when cells are exposed to brefeldin A. Sumoylation on Lys-428 is promoted by the E3 SUMO-protein ligase CBX4. The disease is caused by variants affecting the gene represented in this entry. Belongs to the D-isomer specific 2-hydroxyacid dehydrogenase family.