Fig 6.

Competitive binding assay using in vitro-expressed zebrafish AHR1B or AHR2 proteins. AHR1B (A) and AHR2 (B) proteins were expressed by in vitro transcription and translation, incubated with [³H]TCDD (2 nM) ± 10 nM FICZ or DMSO, and analyzed by velocity sedimentation on sucrose gradients, as described in Materials and Methods. No AHR: Unprogrammed lysate incubated with [³H]TCDD (2 nM), showing nonspecific binding; AHR1B or AHR2 protein incubated with [³H]TCDD (2 nM) + DMSO, showing total binding in the absence of FICZ; AHR1B or AHR2 protein incubated with 2 nM [³H]TCDD + 10 nM FICZ, showing displacement of [³H]TCDD binding by FICZ.