Evolution of human α1-acid glycoprotein genes and surrounding Alu repeats

There is a mosaic pattern of variation between the two tandemly arranged human α₁-acid glycoprotein genes. Both the synonymous and the nonsynonymous sites of exons 3 and 4 are more divergent than the rest of the gene, suggesting that they have had a different evolutionary history. Comparisons of the two gene sequences with rat AGP indicate that exons 3 and 4 of AGP2 have been evolving without functional constraint since their divergence from AGP1. It is proposed that the conserved region of the gene has been homogenized recently by gene conversion with the homologous regions of AGP1. The Alu sequences surrounding the genes appear to have been involved in both the gene duplication and the gene conversion events.