FIG. 1.
Schematic of the organizational structure of the human and murine β-globin gene loci. The human β-globin locus depicted on top consists of five genes which are expressed in a developmental stage-specific manner in erythroid cells as outlined. The expression of the genes is regulated by a locus control region composed of five DNase I HS and located about 15 to 27 kbp upstream of the embryonic ɛ-globin gene. The murine β-globin gene locus, which is depicted on the bottom, consists of four genes which are expressed either in erythroid cells of the embryonic yolk sac (EY or βH1) or in definitive erythroid cells derived from fetal liver or bone marrow hematopoiesis (βmaj and βmin). The murine LCR also contains multiple HS required for high-level globin gene expression.