The ZF-HD ATHB33 protein binds to a core consensus sequence of ATTA. A, Sequences of oligonucleotides used for electrophoretic mobility shift assays. BM1 to 4 represent mutated versions of the B oligonucleotide; mutated residues are underlined. B, Electrophoretic mobility shift assays of radiolabeled A and B oligonucleotides. Specific band shift is indicated by an arrowhead. C, Electrophoretic mobility shift assay using the BM1, BM2, BM3, and BM4 radiolabeled oligonucleotides. D, Competition assay. Increasing concentrations of unlabeled BM1, BM2, BM3, and BM4 oligonucleotides were used to compete for binding of the labeled B oligonucleotide to ATHB33 protein. For B to D, lanes are labeled as follows: probe (labeled oligonucleotide, no protein added); lysate (labeled oligonucleotide plus unprogrammed lysate); luc (labeled oligonucleotide plus luciferase protein control); and ATHB33 (labeled oligonucleotide plus ATHB33 protein).