XIST (gene)

Xist (X-inactive specific transcript) is an RNA gene on the X chromosome of the placental mammals that acts as a major effector of the X inactivation process. It is a component of the Xic - X-chromosome inactivation centre - along with two other RNA genes (Jpx and Ftx) and two protein genes (Tsx and Cnbp2). The Xist RNA, a large (17 kb in humans) transcript, is expressed on the inactive chromosome and not on the active one. It is processed in a similar way to mRNAs, through splicing and polyadenylation. However, it remains untranslated. It has been suggested that this RNA gene evolved at least partly from a protein coding gene that became a pseudogene. The inactive X chromosome is coated with this transcript, which is essential for the inactivation. X chromosomes lacking Xist will not be inactivated, while duplication of the Xist gene on another chromosome causes inactivation of that chromosome.

Function

X inactivation is an early developmental process in mammalian females that transcriptionally silences one of the pair of X chromosomes, thus providing dosage equivalence between males and females (see dosage compensation). The process is regulated by several factors, including a region of chromosome X called the X inactivation center (XIC). The XIST gene is expressed exclusively from the XIC of the inactive X chromosome. The transcript is spliced but apparently does not encode a protein. The transcript remains in the nucleus where it coats the inactive X chromosome. Alternatively spliced transcript variants have been identified, but their full length sequences have not been determined.

2(x)ist

2(X)IST (pronounced "to exist") is an American luxury fashion label that makes men's underwear, swimwear, socks, and watches. The company was founded in 1991 by Gregory Sovell and is headquartered in New York City.

History

2(X)IST was founded in 1991 by Gregory Sovell, who left in 2005. Today, the creative director for 2(X)IST is Jason Scarlatti. The 2(X)IST headquarters is located in midtown Manhattan in New York City.

Notes

External links