The linkage arrangement of four rabbit β-like globin genes

Four different regions of rabbit β-like globin gene sequences designated β1, β2, β3 and β4 were identified in a set of clones isolated from a bacteriophage λ library of chromosomal DNA fragments (Maniatis et al., 1978). Restriction mapping and blot hybridization (Southern, 1975) studies indicate that a subset of these clones containing β1 and β2 hybridizes to an adult β-globin cDNA clone (Maniatis et al., 1976) more efficiently than to a human γ-globin cDNA clone (Wilson et al., 1978), while another subset containing β3 and β4 displays the converse hybridization specificity. β1 was identified as the adult β-globin gene, while β2, β3 and β4 have not been identified with any known rabbit globin polypeptides. Cross-hybridization and transcriptional orientation experiments indicate that the set of β-like gene clones contains overlapping restriction fragments encompassing 44 kb of rabbit chromosomal DNA. In addition, all four genes have the same transcriptional orientation and are arranged in the order 5′-β4-β3-β2-β1-3′.