title: Differences in methylation on the active and inactive human X chromosomes.
abstract: Methylation of CCGG sites was examined in four regions of the X chromosome with four X-chromosome clones, three obtained by cloning random segments and one encoding a structural gene. In DNA from human peripheral blood cells unmethylated sites correlating with the inactive X chromosome were detected in the vicinity of two of the random clones and also in the vicinity of a cloned sequence of the X-linked phosphoglycerate kinase gene (PGK). The third random clone covered a region whose methylation pattern was unchanged between the active and inactive X chromosomes. Differential methylation at the sites detected appears to have no functional role in the maintenance of the inactive X chromosome since both active and inactive X chromosomes were found to be undermethylated in DNA from human lymphoblastoid cells.
mesh_terms: D001483:Base Sequence; D002478:Cells, Cultured; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004262:DNA Restriction Enzymes; D004303:Dosage Compensation, Genetic; D008040:Genetic Linkage; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism; D008745:Methylation; D009693:Nucleic Acid Hybridization; D010735:Phosphoglycerate Kinase / Q000235:genetics; D014960:X Chromosome
chemical_list: D004247:DNA; D010735:Phosphoglycerate Kinase; D004262:DNA Restriction Enzymes