The male-specific region of the human Y chromosome is a mosaic of discrete sequence classes.
Skaletsky H., Kuroda-Kawaguchi T., Minx P.J., Cordum H.S., Hillier L.W., Brown L.G., Repping S., Pyntikova T., Ali J., Bieri T., Chinwalla A., Delehaunty A., Delehaunty K., Du H., Fewell G., Fulton L., Fulton R., Graves T.A., Hou S.-F., Latrielle P., Leonard S., Mardis E., Maupin R., McPherson J., Miner T., Nash W., Nguyen C., Ozersky P., Pepin K., Rock S., Rohlfing T., Scott K., Schultz B., Strong C., Tin-Wollam A., Yang S.-P., Waterston R.H., Wilson R.K., Rozen S., Page D.C.
The male-specific region of the Y chromosome, the MSY, differentiates the sexes and comprises 95% of the chromosome's length. Here, we report that the MSY is a mosaic of heterochromatic sequences and three classes of euchromatic sequences: X-transposed, X-degenerate and ampliconic. These classes contain all 156 known transcription units, which include 78 protein-coding genes that collectively encode 27 distinct proteins. The X-transposed sequences exhibit 99% identity to the X chromosome. The X-degenerate sequences are remnants of ancient autosomes from which the modern X and Y chromosomes evolved. The ampliconic class includes large regions (about 30% of the MSY euchromatin) where sequence pairs show greater than 99.9% identity, which is maintained by frequent gene conversion (non-reciprocal transfer). The most prominent features here are eight massive palindromes, at least six of which contain testis genes.