Figure 1.

Mutagenesis of the chicken β^A-globin gene promoter sequence in pCBALE. The globin sequence (shaded) is numbered with respect to the cap site of the gene. The short bars are CpG dinucleotides. The ovals depict dominant positions adopted by histone octamers in reconstituted chromatin (3): nucleosomes 4 (−427 to −281), 5A (−354 to −208), 5B (−318 to −172) and 6 (−206 to −62). Point mutations (boldface) and CpG dinucleotides (boxed) are indicated for the sense (Watson) strand. Note how the Trip1 and Trip3 sequences, and the Trip23 and Trip25 sequences, are complementary for the 8 bp, −301 to −294, whereas Trip2 is palindromic. Common tetranucleotide sequences are underlined: white, CCGC; grey, GCGG; black, GGCC. The T3 promoter and M13-20 oligonucleotide primers were used in the PCR mutagenesis.