Figure 1.
Features of the X chromosome sequence. a, X chromosome ideogram according to Francke65. b, Evolutionary domains of the X chromosome: the X-added region (XAR), the X-conserved region (XCR; dotted region in proximal Xp does not appear to be part of the XCR), the pseudoautosomal region PAR1, and evolutionary strata S5-S1. c, Sequence scale in intervals of 1 Mb. Note that correlation between cytogenetic band positions and physical distance is imprecise, owing to varying levels of condensation of different Giemsa bands. d, (G+C) content of 100-kb sequence windows. e, Number of genes in 1-Mb sequence windows (pseudogenes not included). f-k, Fractional coverage of 100-kb sequence windows by interspersed repeats: L1 repeats (f), L1M subfamilies of L1 repeats (g), L1P subfamilies of L1 repeats (h), Alu repeats (i), L2 repeats (j), MIR repeats (k). Vertical grey lines in d-k represent gaps in the euchromatic sequence of the chromosome. Grey bar centred at approximately 60 Mb shows the position of the centromere. l, A selection of landmark genes on the chromosome. OPN refers to the three opsin genes in the reference sequence, which are organized as follows: cen-OPN1LW-OPN1MW-OPN1MW-tel. m, Genes that escape from X-chromosome inactivation as previously identified48. n, Cancer-testis antigen genes, belonging to the MAGE (light green), GAGE (dark green), SSX (magenta), SPANX (orange) or other (grey) CT gene families. For the genes in l-n, arrows indicate the direction of transcription.