FREQUENT GENE CONVERSION BETWEEN HUMAN RED AND GREEN OPSIN GENES

To study the evolution of human X-linked red and green opsin genes, ge nomic sequences in large regions of the two genes were compared. The d iver gences in introns 3, 4, and 5 and the 3' flanking sequence of the two genes are significantly lower than those in exons 4 and 5, The ho mogenization mechanism of Introns and the 3' nanking sequence of human red and green opsin genes is probably gene conversion, which also occ urred in exons 1 and 6. At least one gene conversion event occurred in each of three regions (1, 3, and 5) in the sequences compared. In con clusion, gene conversion has occurred frequently between human red and green opsin genes, but exons 2, 3, 4, and 5 have been maintained dist inct between the two genes by natural selection.