Figure 4. Effect of ETR1 disulfide bonds on the ability of the receptor to bind ethylene.

Membranes were isolated from transgenic yeast expressing either wild-type ETR1 (wt) or ETR1(C4S,C6S). Each membrane sample was separated into equal portions, and portions incubated in the absence (M) or presence of 5 mg/mL SB-16 to solubilize the receptor (S), prior to being examined for ethylene binding. Saturable ethylene binding is indicated as the difference between samples treated with ¹⁴C-ethylene (white bars) and identical samples treated with ¹⁴C-ethylene and excess ¹²C-ethylene (overlapping black bars). Results from four independent experiments are shown, with duplicate samples being examined in each experiment.