The orangutan adult α-globin gene locus: Duplicated functional genes and a newly detected member of the primate α-globin gene family

We have cloned and sequenced the complete α1- and α2-globin genes of the orangutan, and here we compare them to the homologous genes of the human. The pattern of similarity apparent among the genes is most consistent with a model of gene correction operating on the primate α-globin cluster. This correction breaks down in both human and orangutan in the 3'-untranslated region at 14 base pairs downstream from the termination codon. The unit evolutionary period values calculated for either the replacement substitution or the silent substitutions are only slightly higher than the previously established molecular clock predicts. The 7-base-pair insertion in intron 2 of the human α1-globin gene is not present in either orangutan gene, suggesting that this insertion is not the cause of the sequence divergence in the 3'-untranslated regions of primate α2- and α1-globin genes. Finally, blotting hybridization and partial DNA sequencing reveal a newly detected number of the primate α-globin gene family, which is located downstream from the duplicated adult α-globin genes.