Kinase PRKY
Kinase Classification: Group AGC: Family PKA: PRKY
DRAFT DATA
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PRKY kinase
PRKY (Protein Kinase, Y-linked) is a Y-chromosome copy of the X-chromosome PRKX found only in chimp and human, to date (few primate Y chromosomes have been sequenced). The predicted chimp gene is full length, and has a testis-expressed cloned cDNA (Genbank: AY728014.1).
Human PRKY lacks exon 6 (57 nt in chimp), and in addition has lost the last nucleotide of exon 5. This causes a frameshift and deletion which removes the last 31 AA of the kinase domain and the PKC-Cterminal domain. 10 ESTs and cDNAs confirm the lack of the end of exon 5 and the altered splicing from exon 5 to exon 7. Exon 6 appears to be deleted, since no homology to chimp exon 6 is seen at this locus.
Apart from human and chimp no other PRKY homologs have been found in cDNA/EST databases, whole genome shotgun datasets or in assembled genomes, though Y chromosomes are frequently not sequenced or undersequenced (if the samples are not all male) or are poorly assembled due to their highly repetitive nature. PRKX and PRKY in human are much more similar than either is to rodent PRKX, further indicating that PRKY is a primate-specific duplication of PRKX.
Comparison of the chimp and human ORFs upstream of the deleted exon, with PRKX from several primates, suggests weakly that PRKY is not under purifying selection in human, and may even be under positive selection in chimp, though the numbers are very low (Ka/Ks = .0016/0.016 for human branch, 0.017/0.002 for chimp, and 0.019/0.030 for common branch, with Macaque PRKX as an outgroup. PRKX values on the same tree are 0.002/0.035 for human, 0.004/0.018 for chimp and 0.002/0.011 for their common branch). However, the possibility of gene conversion between PRKX and PRKY [1] suggests that these results be taken with caution.
PRKY function
No biochemical function for PRKY has been reported, though the transcript is expressed. However, the high sequence similarity between PRKX and PRKY regions can lead to unequal crossing-over during meiosis, and this pair of genes is reported to lead to one third of all cases of (Y+)XX males and (Y-)XY females [2]. This region of the Y chromosome has also been reported as duplicated in one family [3], without any observed phenotype. There may also be some ongoing gene conversion between PRKX and PRKY [1].
References
- Rosser ZH, Balaresque P, and Jobling MA. Gene conversion between the X chromosome and the male-specific region of the Y chromosome at a translocation hotspot. Am J Hum Genet. 2009 Jul;85(1):130-4. DOI:10.1016/j.ajhg.2009.06.009 |
- Schiebel K, Winkelmann M, Mertz A, Xu X, Page DC, Weil D, Petit C, and Rappold GA. Abnormal XY interchange between a novel isolated protein kinase gene, PRKY, and its homologue, PRKX, accounts for one third of all (Y+)XX males and (Y-)XY females. Hum Mol Genet. 1997 Oct;6(11):1985-9. DOI:10.1093/hmg/6.11.1985 |
- Murphy KM, Cohen JS, Goodrich A, Long PP, and Griffin CA. Constitutional duplication of a region of chromosome Yp encoding AMELY, PRKY, and TBL1Y: implications for sex chromosome analysis and bone marrow engraftment analysis. J Mol Diagn. 2007 Jul;9(3):408-13. DOI:10.2353/jmoldx.2007.060198 |
Contributors/History
Gerard 15:17, 15 August 2011 (PDT)
