A gene located in the X chromosome inactivation center of humans at Xq13. The homologous gene in the mouse is symbolized Xist. XIST is the acronym for X-Inactive Specific Transcript, and the major transcript is an RNA molecule about 19 kb long. Shorter transcripts are also generated by alternative splicing (q.v.). The XIST gene is 232,103 base pairs long. The euchromatic part of the X is six times longer than that of the Y. XIST RNA is transcribed in the nuclei of female somatic cells, where it coats the X chromosome and causes its inactivation. The transcribing gene is on the chromosome that is being silenced. Chromosomal regions subject to inactivation are enriched with DNA LINE-1 elements. These L1 elements may serve as targets to which XIST RNAs bind. See Chronology, 1996, Penny et al.; 1998, Lyon; repetitious DNA, X-chromosome inactivation.
Subjects: Genetics and Genomics.