THE UTX GENE ESCAPES X-INACTIVATION IN MICE AND HUMANS

We recently have identified a ubiquitously transcribed mouse Y chromos ome gene, Uty, which encodes a tetratricopeptide repeat (TPR) protein, A peptide derived from the UTY protein confers H-Y antigenicity on ma le cells, Here we report the characterization of a widely transcribed X-linked homologue of Uty,called Utx, which maps to the proximal regio n of the mouse X chromosome and which detects a human X-linked homolog ue at Xp11.2, Given that Uty is ubiquitously transcribed, we assayed f or Utx expression from the inactive X chromosome (Xi) in mice and foun d that Utx escapes X chromosome inactivation, Only Smcx and the pseudo autosomal Sts gene on the mouse X chromosome have been reported previo usly to escape inactivation. The human UTX gene was also found to be e xpressed from Xi. We discuss the significance of these data for our un derstanding of dosage compensation of X-Y homologous genes in humans a nd mice.