Figure 1.

Structure of the wild-type and mutant human β-globin YACs. (A) YAC clone A201F4 (22) was modified as described (26) to permit ease of manipulation for targeted mutagenesis in yeast. Expanded diagrams depicting the two targeting constructs generated here are shown above (the ɛ-globin silencer deletion mutant) or below (the β-globin enhancer deletion mutant) the diagram of the YAC clone (the position of the deleted elements is indicated by a break in the contiguity of the subclone). Note the position of the SfiI and SalI sites in the locus that were used in the mapping experiments described in Fig. 2. (B Upper) An ethidium bromide-stained pulse field gel of the wild-type, ɛ-silencer, and β-enhancer deletion mutant YACs. (B Lower) Autoradiographic exposure of the blots of the gels shown in the Upper panel after hybridization to probes corresponding to the ɛ-globin gene silencer (Left) or β-globin gene enhancer (Right). (C) Southern blots of both wild-type and mutant YAC DNAs depicting the size and integrity of the EcoRI fragments bearing the LCR and the ɛ-, γ-, and β-globin genes.