In the field of molecular biology

Molecular biology

Molecular biology is the branch of biology that deals with the molecular basis of biological activity. This field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry...

, transrepression is a process whereby one protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 represses (i.e., inhibits) the activity of a second protein through a protein-protein interaction

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...

. Since this repression occurs between two different protein molecules (intermolecular), it is referred to as a trans-acting

Trans-acting

In the field of molecular biology, trans-acting , in general, means "acting from a different molecule"...

 process.

The protein that is repressed is usually 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...

 whose function is to up-regulate (i.e., increase) the rate of gene transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

. Hence the net result of transrepression is down regulation of gene transcription.

The phenomenon of transrepression was first observed in the ability of the glucocorticoid receptor

Glucocorticoid receptor

The glucocorticoid receptor also known as NR3C1 is the receptor to which cortisol and other glucocorticoids bind....

 to inhibit the transcriptional promoting activity of the AP-1 and NF-κB transcription factors. In addition to transactivation

Transactivation

In molecular biology and genetics, transactivation is an increased rate of gene expression triggered either by biological processes or by artificial means.- Natural transactivation :...

, transrepression is an important pathway for the anti-inflammatory

Anti-inflammatory

Anti-inflammatory refers to the property of a substance or treatment that reduces inflammation. Anti-inflammatory drugs make up about half of analgesics, remedying pain by reducing inflammation as opposed to opioids, which affect the central nervous system....

 effects of glucocorticoid

Glucocorticoid

Glucocorticoids are a class of steroid hormones that bind to the glucocorticoid receptor , which is present in almost every vertebrate animal cell...

s. Since then, other nuclear receptor

Nuclear receptor

In the field of molecular biology, nuclear receptors are a class of proteins found within cells that are responsible for sensing steroid and thyroid hormones and certain other molecules...

s such as LXR

Liver X receptor

The liver X receptor is a member of the nuclear receptor family of transcription factors and is closely related to nuclear receptors such as the PPARs, FXR and RXR. Liver X receptors are important regulators of cholesterol, fatty acid, and glucose homeostasis...

 and PPAR

Peroxisome proliferator-activated receptor

In the field of molecular biology, the peroxisome proliferator-activated receptors are a group of nuclear receptor proteins that function as transcription factors regulating the expression of genes...

have been demonstrated to also have the ability to transrepress the activity of other proteins.