High impact information on Xlr

• The meiosis-specific Xmr gene product is homologous to the lymphocyte Xlr protein and is a component of the XY body [1].
• The Xlr (X-chromosome linked, lymphocyte regulated) multigene family was previously found to determine, in the lymphoid cell lineage, the stage-specific expression of a nuclear protein with a primary sequence suggestive of a transcriptional activator function [1].
• We report here the characterization of a second functional member of the Xlr gene family that is abundantly transcribed in testis in a tissue-specific and developmentally regulated manner [1].
• These findings indicate a sex-specific expression of two closely related members of the Xlr gene family during meiotic prophase I [2].
• In addition, because of the localization of the Xlr sequence family on the mouse X chromosome, the human equivalent of Xlr is a candidate gene for premature ovarian failure [2].

Biological context of Xlr

• Xlr3a and Xlr3b are members of a new subfamily in the Xlr multigene family [3].
• The protein product of this newly identified gene, called Xmr (Xlr-related, meiosis regulated), is located in the nuclei of spermatocytes, early in the prophase of the first meiotic division, and later becomes concentrated in the XY nuclear subregion where it is in particular associated with the axes of sex chromosomes [1].
• Instead, Xlr (X linked, lymphocyte regulated), a closely related gene expressed in fetal thymus cells at the time of antigen-receptor gene rearrangement, was expressed in oocytes throughout meiotic prophase I [2].
• Sex-specific gene expression during meiotic prophase I: Xlr (X linked, lymphocyte regulated), not its male homologue Xmr (Xlr related, meiosis regulated), is expressed in mouse oocytes [2].
• This accumulation of pseudogenes may be related to the evolutionarily recent amplification of Xlr in rodents [4].

Anatomical context of Xlr

• Both the lymphoid and the germinal cell Xlr proteins are located in the cell nucleus and are closely homologous to each other [4].
• In contrast, no Xlr-immunoreactive protein was detected in a series of human tissues including brain, skeletal muscle, colon, liver, and kidney, revealing a tissue-specific expression pattern similar to that of murine Xlr [5].

Other interactions of Xlr

• The Xlr (X-linked lymphocyte regulated) gene family (a candidate locus for an X-linked primary immune deficiency) [4].

References