Codon usage in the vertebrate hemoglobins and its implications

A study of codon usage in vertebrate hemoglobins revealed an evolutionarytrend toward elevated numbers of CpG codon boundary pairs in mammalianhemoglobin alpha genes. Selection for CpG codon boundaries countering thegenerally observed CpG suppression is strongly suggested by these data.These observations parallel recently published experimental results thatindicate that constitutive expression of the human alpha-globin geneappears to be determined by regulatory information encoded within thestructural gene. The possibility is raised that, in the absence ofselection, CpG decay can be used to date the evolutionary origin of amammalian alpha pseudogene from its active alpha gene.