FIG. 8.

Effects of TATA box mutations on transcription and promoter restriction enzyme accessibility. (A) RNase protection was used to measure the abundance of ɛ-globin transcripts. The relative amount of ɛ-globin RNA was determined as detailed in the legend to Fig. 4B. Mean levels of expression of ɛ-globin RNA and SEM for several individual clones with the TATA box mutation are shown. (B) Nuclei were digested as detailed in the legend to Fig. 3B but with AvaII or NcoI to determine promoter accessibility. The positions of AvaII and NcoI cleavage within the ɛ-globin promoter are shown in the diagram at the bottom. Lane Kb, markers with sizes given in kilobases at the right. (C) Accessibility at promoter AvaII and NcoI sites and accessibility at the HS2 MscI site for clones a to d are compared to the values for ɛ and ɛHS2 wild-type minichromosomes (see Materials and Methods).