C-terminal-binding protein 1 also known as CtBP1 is a protein that in humans is encoded by the CTBP1 gene. [5] CtBP1 is one of two CtBP proteins, the other protein being CtBP2. [6]
The CtBP1 protein was originally identified as a human protein that bound a PLDLS motif in the C-terminus of adenovirus E1A proteins. It and the related protein CTBP2 were later shown to function as transcriptional corepressors. [7] That is, regulatory proteins that bind to sequence-specific DNA-binding proteins and help turn genes off. CtBPs do this by recruiting histone modifying enzymes that add repressive histone marks and remove activating marks. CtBP proteins can also self-associate and presumably bring together gene regulatory complexes. [8]
CtBP1 is broadly expressed from embryo to adult, while CtBP2 has a somewhat more restricted pattern of expression. CtBPs have multiple biological roles and appear to be most important in regulating the epithelial to mesenchymal transition, as well as influencing metabolism. They do the latter by binding NADH in preference to NAD+, thereby sensing the NADH/NAD+ ratio. When bound, it undergoes a conformational change that allows it to dimerize and associate with its partner proteins and silence specific genes.
During skeletal and T cell development, CtBP1 and CtBP2 associate with the PLDLSL domain of δEF1, a cellular zinc finger-homeodomain protein, and thereby enhances δEF1-induced transcriptional silencing. CtBP also binds the Kruppel-like factors family of zinc finger proteins KLF3, KLF8 and KLF12. In addition, CtBP complexes with CtIP, a 125 kDa protein that recognizes distinctly different protein motifs from CtBP. CtIP binds to the BRCT repeats within the breast cancer gene BRCA1 and enables CtBP to influence BRCA1 activity. Both proteins can also interact with a polycomb group protein complex which participates in regulation of gene expression during development. Alternative splicing of transcripts from this gene results in multiple transcript variants. [9]
C-terminal-binding protein interacting protein (CtIP) is a binding partner with CtBP, which contribute to transcription repression and cell cycle regulation, and which have a role in the cellular response to DNA damage. [10]
CTBP1 has been shown to interact with:
Histone acetyltransferase p300 also known as p300 HAT or E1A-associated protein p300 also known as EP300 or p300 is an enzyme that, in humans, is encoded by the EP300 gene. It functions as histone acetyltransferase that regulates transcription of genes via chromatin remodeling by allowing histone proteins to wrap DNA less tightly. This enzyme plays an essential role in regulating cell growth and division, prompting cells to mature and assume specialized functions (differentiate), and preventing the growth of cancerous tumors. The p300 protein appears to be critical for normal development before and after birth.
In molecular genetics, the Krüppel-like family of transcription factors (KLFs) are a set of eukaryotic C2H2 zinc finger DNA-binding proteins that regulate gene expression. This family has been expanded to also include the Sp transcription factor and related proteins, forming the Sp/KLF family.
Histone deacetylase 1 (HDAC1) is an enzyme that in humans is encoded by the HDAC1 gene.
The nuclear receptor co-repressor 1 also known as thyroid-hormone- and retinoic-acid-receptor-associated co-repressor 1 (TRAC-1) is a protein that in humans is encoded by the NCOR1 gene.
Nuclear receptor-interacting protein 1 (NRIP1) also known as receptor-interacting protein 140 (RIP140) is a protein that in humans is encoded by the NRIP1 gene.
Activating transcription factor 2, also known as ATF2, is a protein that, in humans, is encoded by the ATF2 gene.
E3 SUMO-protein ligase PIAS1 is an enzyme that in humans is encoded by the PIAS1 gene.
E3 SUMO-protein ligase PIAS2 is an enzyme that in humans is encoded by the PIAS2 gene.
Histone deacetylase 9 is an enzyme that in humans is encoded by the HDAC9 gene.
Homeobox protein TGIF1 is a protein that, in humans, is encoded by the TGIF1 gene. Alternative splicing has been observed at this locus and eight variants, encoding four distinct isoforms, are described.
DNA methyltransferase 1-associated protein 1 is an enzyme that in humans is encoded by the DMAP1 gene.
Retinoblastoma-binding protein 8 is a protein that in humans is encoded by the RBBP8 gene.
C-terminal-binding protein 2 also known as CtBP2 is a protein that in humans is encoded by the CTBP2 gene.
Ran-specific binding protein 1 is an enzyme that in humans is encoded by the RANBP1 gene.
Zinc finger MYND domain-containing protein 11 is a protein that in humans is encoded by the ZMYND11 gene.
Transcription factor E4F1 is a protein that in humans is encoded by the E4F1 gene.
NGFI-A-binding protein 2 also known as EGR-1-binding protein 2 or melanoma-associated delayed early response protein (MADER) is a protein that in humans is encoded by the NAB2 gene.
Krueppel-like factor 12 is a protein that in humans is encoded by the KLF12 gene.
Krüppel-like factor 3 is a protein that in humans is encoded by the KLF3 gene.
In molecular biology the MYND-type zinc finger domain is a conserved protein domain. The MYND domain is present in a large group of proteins that includes RP-8 (PDCD2), Nervy, and predicted proteins from Drosophila, mammals, Caenorhabditis elegans, yeast, and plants. The MYND domain consists of a cluster of cysteine and histidine residues, arranged with an invariant spacing to form a potential zinc-binding motif. Mutating conserved cysteine residues in the DEAF-1 MYND domain does not abolish DNA binding, which suggests that the MYND domain might be involved in protein-protein interactions. Indeed, the MYND domain of ETO/MTG8 interacts directly with the N-CoR and SMRT co-repressors. Aberrant recruitment of co-repressor complexes and inappropriate transcriptional repression is believed to be a general mechanism of leukemogenesis caused by the t(8;21) translocations that fuse ETO with the acute myelogenous leukemia 1 (AML1) protein. ETO has been shown to be a co-repressor recruited by the promyelocytic leukemia zinc finger (PLZF) protein. A divergent MYND domain present in the adenovirus E1A binding protein BS69 was also shown to interact with N-CoR and mediate transcriptional repression. The current evidence suggests that the MYND motif in mammalian proteins constitutes a protein-protein interaction domain that functions as a co-repressor-recruiting interface.