Binding of the AhR-ARNT complex to the TCDD-responsive sequence in the TH enhancer. The sequence is obtained from the murine TH gene 5'-flanking region (-285 to -167 bp). Each of the five underlined sequences (sequences A-E) was used as a TH 5'-flanking oligonucleotide probe for EMSA. (B) Alexa Fluor 532-labeled probes (sequences A-E) were incubated with the components indicated above each lane. EMSA signals were detected using a Typhoon 8600 fluorescent scanner. Black arrow indicates specific signal from the DNA-protein complex. In the presence of TCDD, the AhR-ARNT complex bound to sequence C (lane 3). (C) Using Alexa Fluor 532-labeled sequence C, EMSA was performed with and without unlabeled XRE probe as a competitor. In the presence of ARNT, the AhR-ARNT complex bound to sequence C (lane 1). This signal increased on exposure to 1 μM TCDD (lane 2) and decreased in the presence of unlabeled XRE as a competitor (lane 3). Data represent triplicate experiments.