FIGURE 6.

Comparison of ethylene binding to ETR1[1–128]-GST with copper sulfate versus silver nitrate. Ethylene binding was determined for membranes isolated from yeast expressing ETR1[1–128]-GST. Membranes were pre-incubated with either 300 μm copper sulfate or silver nitrate for 30 min prior to determining saturable ethylene binding. In both panels, the mean normalized level of ¹⁴C₂H₄ bound ± S.D. is shown. A, time course of ¹⁴C₂H₄ dissociation from ETR1[1–128]-GST was determined after binding was carried out with 0.1 μl/liter ¹⁴C₂H₄. Samples were aired for the indicated times in a chamber with a continuous flow of humidified air and analyzed for ¹⁴C₂H₄ remaining. Data for each incubation condition were normalized to the level of ethylene binding after airing for 10 min. B, ethylene binding levels with 1 μl/liter ¹⁴C₂H₄ in the presence of increasing amounts of ¹²C₂H₄ at the indicated concentrations were determined. Data were normalized in each condition to the levels of binding in the absence of added ¹²C₂H₄.