Rabbit globin pseudogene psi beta 2 is a hybrid of delta- and beta-globin gene sequences

The evolutionary history of the rabbit globin pseudogene psi beta 2 wasstudied by completing its nucleotide sequence and aligning the sequencewith that of the rabbit adult globin gene beta 1 and the human minor adultglobin gene delta. The 5' flanking region and exon 1 of psi beta 2 weremost similar to rabbit beta 1, but the large intervening sequence and the3' untranslated region were most similar to human delta. Intron 1 and exon2 were equally similar to both delta and beta 1. This pattern indicatesthat psi beta 2 was originally a delta-like gene that acquired the 5'portion of gene beta 1 by intrachromosomal gene conversion. The presence ofa delta-globin gene sequence in both rabbits and humans shows that it is anancient gene, predating the mammalian radiation that occurred over 85 Myrago. Delta has shown a pronounced tendency to be altered in its 5' endduring the course of mammalian evolution. Quantitative divergence analysisshows that the ancestor to rabbit psi beta 2 was active until 20-30 Myrago, during which time the lagomorph beta-globin gene family apparentlyfunctioned without a pseudogene.