FIGURE 4.

The effects of copper sulfate and silver nitrate on ethylene binding activity in members of the ethylene receptor family from Arabidopsis. Ethylene binding to equal amounts of yeast membranes isolated from yeast cells expressing the binding domain of each receptor isoform fused to GST or empty vector was compared between samples treated with ¹⁴C₂H₄ (0.1 μl/liter) and identical samples treated with ¹⁴C₂H₄ (0.1 μl/liter) plus ¹²C₂H₄ (1000 μl/liter). Samples were pre-incubated for 30 min with either 300 μm copper sulfate, silver nitrate or no metal. Displaceable ethylene binding was determined by subtracting the amount of ¹⁴C₂H₄ bound in the presence of excess ¹²C₂H₄ from the amount of ¹⁴C₂H₄ in the absence of added ¹²C₂H₄. Data show the mean counts per minute ± S.D.