Inactive X chromosome DNA does not function in DNA-mediated cell transformation for the hypoxanthine phosphoribosyltransferase gene.

Abstract

The molecular nature of the X chromosome inactivation process was investigated utilizing the techniques of DNA-mediated cell transformation of the X-linked hypoxanthine phosphoribosyltransferase (HPRT; EC 2.4.2.8) locus. Purified DNA from the inactive X chromosome of a near-euploid mouse cell line is not functional in transformation for HPRT, but the DNA from its homologous active X readily elicits transformation for HPRT in the same hamster cell recipient. There is a difference between the DNA, per se, of the active and inactive X at (or near) the HPRT locus and that this difference could account, at least in part, for its inactivation.