Binding of +-MITF to the CACTTG motif in the 5′ flanking region of the p75 gene. (A) EGMSA using GST-+-MITF and GST-mi-MITF fusion proteins. The 5′-ACGCCTCACTTGACTGCTCTGGACT oligonucleotide containing a CACTTG motif (probe 1, nt −149 to −125; numbers refer to the sequence shown in Fig 2) and the 5′-TGCCTTCACCCAGCTGCTCCCG oligonucleotide containing a CAGCTG motif (probe 2, nt −31 to −10) were used (CANNTG motifs are boxed). The DNA-protein complex is indicated by an arrowhead. (B) Competitive DNA binding assay with GST-+-MITF. Two competitors were synthesized. Oligo 1 was identical to probe 1; oligo 3 had the mutation at the CACTTG motif (to CTCTAG). DNA-protein complexes are indicated by an arrowhead.