HERV-W_7q21.2 provirus ancestral Env polyprotein also known as Env-W or enverin or syncytin is a 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...

 that in humans is encoded by the ERVWE1 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...

.

Function

Many different human endogenous retrovirus

Endogenous retrovirus

Endogenous retroviruses are sequences in the genome thought to be derived from ancient viral infections of germ cells in humans, mammals and other vertebrates; as such their proviruses are passed on to the next generation and now remain in the genome....

 (HERV) families are expressed in normal placental tissue at high levels, suggesting that HERVs are functionally important in reproduction. This gene is part of an HERV provirus on chromosome 7 that has inactivating mutations in the gag and pol genes. This gene is the envelope glycoprotein gene which appears to have been selectively preserved. The product of this gene, syncytin, is expressed in the placental syncytiotrophoblast

Syncytiotrophoblast

Syncytiotrophoblast is the epithelial covering of the placenta villous tree. It is a unique tissue in that it is a multi-nucleated, terminally differentiated syncytium, extending to 13m^2...

 and is involved in fusion of the cytotrophoblast

Cytotrophoblast

The cytotrophoblast is the inner layer of the trophoblast, interior to the syncytiotrophoblast in an embryo.Cytotrophoblast is considered to be the trophoblastic stem cell; it differentiates into the other forms of trophoblastic tissue .-External links: - "Female Reproductive System: placental...

 cells to form the syncytial layer of the placenta. The protein has the characteristics of a typical retroviral envelope protein, including a furin

Furin

Furin is a protein that in humans is encoded by the FURIN gene. It was named furin because it was in the upstream region of an oncogene known as FES. The gene was known as FUR and therefore the protein was named furin...

 cleavage site that separates the surface (SU) and transmembrane (TM) proteins which form a heterodimer.

Clinical significance

HERV-W has been associated with multiple sclerosis

Multiple sclerosis

Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...

 and schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

 in humans.

External links

• ERVWE1 on the Atlas of Genetics and Oncology
  Atlas of Genetics and Cytogenetics in Oncology and Haematology
  The Atlas of Genetics and Cytogenetics in Oncology and Haematology is a collection of resources on genes, chromosomes anomalies, leukemias, solid tumours, and cancer-prone diseases...