Structure and organization of the bovine beta-globin genes

Genomic clones spanning the entire cow beta-globin gene locus have beenisolated and characterized. These clones demonstrate that the linkage ofembryonic-like (epsilon) genes and pseudogenes (psi) to the previouslydescribed fetal (gamma) and adult (beta) genes is as follows: 5'-epsilon3-epsilon 4-psi 3-beta-epsilon 1-epsilon 2-psi 1- psi 2-gamma-3'. Presentdata indicate that, like that of the goat, the fetal and adult genes arosevia block duplication of an ancestral four- gene set:epsilon-epsilon-psi-beta. This duplication event preceded the divergence ofcows and goats, which occurred greater than or equal to 18-20 Myr ago.However, cows do not have the additional four-gene block containing apreadult/stress globin gene (beta C). Furthermore, the cow fetal clustercontains an extra beta-like pseudogene, which apparently arose by asmall-scale duplication. The fixation of this duplication may indicate apossible evolutionary role for pseudogenes.