Human Molecular Genetics Advance Access originally published online on April 27, 2006
Human Molecular Genetics 2006 15(11):1870-1875; doi:10.1093/hmg/ddl109
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Origination and evolution of a human-specific transmembrane protein gene, c1orf37-dup
1Key Laboratory of Bioresources Conservation and Utilization and Human Genetics Center of Yunnan University, Kunming 650091, PR China, 2CAS-Max Planck Junior Research Group and Key Laboratory of Cellular and Molecular Evolution, Kunming Institute of Zoology and 3Kunming Primate Research Center, Chinese Academy of Sciences, Kunming 650223, PR China and 4Graduate School of Chinese Academy Sciences, Beijing 100039, PR China
* To whom the correspondence should be addressed at: Kunming Institute of Zoology, No. 32 E. Jiao Chang Road, Kunming, Yunnan 650223, PR China. Tel: +86 8715192979; Fax: +86 8715193137; Email: wwang{at}mail.kiz.ac.cn or Yunnan University, No. 2 N. Cuihui Road, Kunming, Yunnan 650091, PR China. Tel and Fax: +86 8715034636; Email: cjxiao2005{at}yahoo.com.cn
Received January 26, 2006; Accepted April 14, 2006
A transmembrane protein gene, c1orf37-dup, was identified as a young gene specific to humans. It was derived from the conserved c1orf37 gene through retroposition after the divergence of human and chimpanzee. This gene has evolved rapidly driven by positive Darwinian selection as evident from a significantly high ratio of non-synonymous substitution rate to synonymous substitution rate (Ka/Ks=2.08) between the new c1orf37-dup and the parental c1orf37 genes. Population genetics analysis disclosed a very low level of polymorphism in the c1orf37-dup gene and its neighboring regions, thus providing support for the occurrence of a recent selective sweep. The GFP experiments revealed that it encodes a transmembrane protein associated with cell membranes. Non-random distribution of amino acid changes indicates the C1ORF37-DUP protein may have evolved diverged functions in the presumably functionally important N-terminal region in the cytoplasm and the extracellular loop. These lines of evidence support that the functional adaptation of c1orf37-dup has occurred in humans. Unlike its ubiquitously expressed parental gene, c1orf37-dup expresses selectively in several human tissues including brain. It is suggested that c1orf37-dup encodes a novel transmembrane protein in humans which potentially endows new properties to cell surface interactions.
The c1orf37-dup gene and its flanking region (region A in Fig. 4B): DQ186292–DQ186413. The neighboring region D: DQ186414–DQ186427, region C: DQ186428–DQ186447, region B: DQ186448–DQ186461 and region E: DQ186462–DQ186475.