The human β-globin locus is composed of five genes located on a short region of chromosome 11, responsible for the creation of the beta parts (roughly half) of the oxygen transport protein Haemoglobin.
[1] The order of the genes in the beta-globin cluster is: 5' - epsilon – gamma-G – gamma-A – delta – beta - 3'.
Many CRMs have been mapped within the cluster of genes encoding β-like globins expressed in embryonic (HBE1), fetal (HBG1 and HBG2), and adult (HBB and HBD) erythroid cells.
All are marked by DNase I hypersensitive sites and footprints, and many are bound by GATA1 in peripheral blood derived erythroblasts (PBDEs).
An enhancer located 3′ of the HBG1 gene is bound by several proteins in PBDEs and K562 cells and is sensitive to DNase I, but shows almost no signal for mammalian constraint.