CpG islands of the X chromosome are gene associated.
Unmethylated CpG rich islands are a feature of vertebrate DNA: they are associated with housekeeping and many tissue specific genes. CpG islands on the active X chromosome of mammals are also unmethylated. However, islands on the inactive X chromosome are heavily methylated. We have identified a CpG island in the 5' region of the G6PD gene, and two islands forty Kb 3' from the G6PD gene, on the human X chromosome. Expression of the G6PD gene is associated with concordant demethylation of all three CpG islands. We have shown that one of the two islands is in the promoter region of a housekeeping gene, GdX. In this paper we show that the second CpG island is also associated with a gene, P3. The P3 gene has no homology to previously described genes. It is a single copy, 4 kb gene, conserved in evolution, and it has the features of a housekeeping two genes is within the CpG island and that sequences in the islands have promoter function.
Alcalay
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M
International Institute of Genetics and Biophysics, CNR, Naples, Italy.
Toniolo
D
D
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000302:isolation & purification; D004247:DNA / Q000302:isolation & purification; D015226:Dinucleoside Phosphates / Q000235:genetics*; D005091:Exons; D005796:Genes; D006801:Humans; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D009710:Nucleotide Mapping; D011401:Promoter Regions, Genetic; D014960:X Chromosome
D002868:Chromosomal Proteins, Non-Histone; D004247:DNA; D015226:Dinucleoside Phosphates; C015772:CpG dinucleotide