Vol. 38 No. 4, 1999

Molecular Evolutionary Analyses of the Rh Blood Group Genes and Rh50 Genes in Mammals

Takashi Kitano, Satoshi OOta and Naruya Saitou*

Laboratory of Evolutionary Genetics, National Institute of Genetics, Mishima 411-8540, Japan

Takashi Kitano, Satoshi OOta and Naruya Saitou (1999) All mammals probably possess the Rh blood group gene and its homologous Rh50 gene coded membrane proteins. In this study, we compared nucleotide sequences of Rh and Rh50 genes for primates and rodents. We found that the rates of synonymous substitutions of both genes were roughly constant, and the divergence time between mouse and rat was estimated to be about 30 million years ago (mya). Heterogeneity of the evolutionary rate between primates and rodents was suggested. We also compared amino acid changes of outer-, inner-, and trans-membrane regions of the Rh and Rh50 proteins. Amino acid changes of outer-membrane regions were more frequent except for primate Rh genes. To obtain an improved estimation of divergence time, it is better to have multiple calibration points for the molecular clock. The time of gene duplication that produced the Rh and Rh50 genes was estimated to be about 340-380 mya.

Key words: Rh and Rh50 genes, Relative rates, Divergence time.

*Correspondence: Tel: 81-559-816790. Fax: 81-559-816789. E-mail: nsaitou@genes.nig.ac.jp