Transcriptional repressor CTCF also known as 11-zinc finger protein or CCCTC-binding factor is a transcription factor

Transcription factor

In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...

 that in humans is encoded by the CTCF gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

. CTCF is involved in insulator

Insulator (genetics)

An insulator is a genetic boundary element that plays two distinct roles in gene expression, either as an enhancer-blocking element, or more rarely as a barrier against condensed chromatin proteins spreading onto active chromatin...

 activity.

Function

The protein CTCF plays heavily in the role of repressing the insulin-like growth factor 2

Insulin-like growth factor 2

Insulin-like growth factor 2 is one of three protein hormones that share structural similarity to insulin.-Gene structure:In humans, the IGF2 gene is located on chromosome 11p15.5, a region which contains numerous imprinted genes. In mice this homologous region is found at distal chromosome 7...

 gene, by binding to the H-19 imprinting control region (ICR) along with differentially-methylated region-1 (DMR1) and MAR3.

Binding of targeting sequence elements by CTCF can block the interaction between enhancers and promoters, therefore limiting the activity of enhancers to certain functional domains. Besides acting as enhancer blocking, CTCF can also act as a chromatin barrier by preventing the spread of heterochromatin structures.

The human genome contains nearly 15,000 CTCF insulator sites, suggesting a widespread role of CTCF in gene regulation. In addition CTCF binding sites act as nucleosome positioning anchors so that, when used to align various genomic signals, multiple flanking nucleosomes can be readily identified.

Interactions

CTCF has been shown to interact

Protein-protein interaction

Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...

 with Y box binding protein 1

Y box binding protein 1

Y box binding protein 1, officially known as YBX1, but commonly referred to as "YB-1" by researchers, is a human protein. Current research is examining its involvement in cancer, and particularly in the metastasis of cancerous cells or prevention thereof....

.

CTCF also co-localizes with cohesin

Cohesin

Cohesin is a protein complex that regulates the separation of sister chromatids during cell division, either mitosis or meiosis.- Structure :...

, which stabilizes the repressive loops organized by the CTCF.