Chromatin structure and organization of the γ-globin gene promoter. (A) Potential changes in adult-stage chromatin structure from condensed (left) to flexible (right) induced by binding of GG1-VP64 (tennis ball structure) to the γ-globin gene promoters. Interactions that exist between the LCR and delta (δ)- and beta-(β) globin genes during normal adult erythroid development compared with potential new interactions between the LCR and the γ-globin genes caused by binding of GG1-VP64 are shown (adapted from Bank2 with permission). (B) Location of binding sites for selected endogenous transcriptional activators (shaded light gray) and repressors (shaded dark gray) within the proximal γ-globin gene promoter with respect to the HPFH-117 target sequence. KLF11 indicates fetal Kruppel-like factor; HPFH, hereditary persistence of HbF; NF-Y, nuclear transcription factor-Y; CP2; transcription factor CP2; and NF-E4, nuclear transcription factor-erythroid 4.
