Retroposition of autosomal mRNA yielded testis-specific gene family on human Y chromosome

  • An Erratum to this article was published on 01 June 1999


Most genes in the human NRY (non-recombining portion of the Y chromosome) can be assigned to one of two groups: X-homologous genes or testis-specific gene families with no obvious X-chromosomal homologues1,2. The CDY genes have been localized to the human Y chromosome1, and we report here that they are derivatives of a conventional single-copy gene, CDYL (CDY-like), located on human chromosome 13 and mouse chromosome 6. CDY genes retain CDYL exonic sequences but lack its introns. In mice, whose evolutionary lineage diverged before the appearance of the Y-linked derivatives, the autosomal Cdyl gene produces two transcripts; one is expressed ubiquitously and the other is expressed in testes only. In humans, autosomal CDYL produces only the ubiquitous transcript; the testis-specific transcript is the province of the Y-borne CDY genes. Our data indicate that CDY genes arose during primate evolution by retroposition of a CDYL mRNA and amplification of the retroposed gene. Retroposition contributed to the gene content of the human Y chromosome, together with two other molecular evolutionary processes: persistence of a subset of genes shared with the X chromosome3,4 and transposition of genomic DNA harbouring intact transcription units5.

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Figure 1: Human CDY proteins and transcripts.
Figure 2: Comparison of transcripts and encoded proteins from mouse Cdyl, human CDYL and human CDY1 genes.
Figure 3: Homologues of CDYL and CDY in diverse mammalian species.
Figure 4: Tissue distributions of mouse Cdyl, human CDYL and human CDY transcripts.
Figure 5: Schematic representation of three molecular evolutionary processes that contributed genes to human NRY.

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We thank H. Skaletsky and F. Lewitter for assistance with sequence analysis; the San Diego Zoo and the Duke Primate Center for animal specimens; and P. Bain, A. Bortvin, L. Brown, C. Burge, B. Charlesworth, A. Chess, S. Gilbert, R. Jaenisch, T. Kawaguchi, K. Kleene, D. Menke, R. Saxena, C. Sun, C. Tilford and J. Wang for helpful discussions and comments on the manuscript.

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Correspondence to David C Page.

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