title: Closely related sequences on human X and Y chromosomes outside the pairing region.
abstract: During meiosis the human X and Y chromosomes form a synaptonemal complex which covers most of Yp and the terminal 30% of Xp (ref. 1). By analogy with the autosomes, this is presumed to reflect DNA sequence homology. It has been suggested that these regions of the X and Y chromosomes contain either related or identical loci which are distal to a site of cross-over, and support for these ideas has come from the finding that an X-linked cell-surface antigen controlling gene MIC2 is related to a gene on the Y chromosome. A number of DNA sequences have been shown to occur either on the X and Y chromosomes or on the X, Y and autosomes. We have now isolated a sequence from the Y chromosome which is present on Xq and Yq. This region lies well outside the pairing segments, and sequence analysis reveals no base change in 1 kilobase pair (kb). This high degree of similarity between the X and Y chromosomes near the tips of the long arms is a strong indication that interchange can occur in this region.
mesh_terms: D001483:Base Sequence; D003434:Crossing Over, Genetic; D004262:DNA Restriction Enzymes; D005260:Female; D006801:Humans; D008297:Male; D008540:Meiosis; D009693:Nucleic Acid Hybridization; D014960:X Chromosome / Q000502:physiology*; D014998:Y Chromosome / Q000502:physiology*
chemical_list: D004262:DNA Restriction Enzymes