Figure 1.

EIN2 is a short-lived protein whose accumulation is essential for ethylene responses. (A) EIN2 is a short half-life protein. Etiolated wild-type Col-0 seedlings grown in air supplied in the presence of 100 μM CHX for different amounts of time. Total protein lysates were subjected to immunoblotting with EIN2 antiserum. Coomassie blue staining of total membrane proteins was used as a lane loading control. (B) The protein level of EIN2 is stabilized by specific proteasome inhibitors. Total membrane protein extracts were derived from wild-type Col-0 etiolated seedlings treated with mock (1% DMSO), MG132 (50 μM), MG115 (50 μM) for 1 or 4 h, and used for immunoblot assays. (C) EIN2 accumulation is abolished by Ag⁺ treatment. Etiolated wild-type seedlings were grown on MS media without or with 100 μM AgNO₃ for 3 d and treated with air or ethylene for the indicated amount of time. (D) EIN2 protein level is impaired in etr1-1 mutant seedlings and constitutively accumulates in ctr1-1 mutant seedlings. Wild-type Col-0, ctr1-1, etr1-1, and ein3-1eil1-1 mutant etiolated seedlings were grown on MS media in air for 3 d and subsequently treated with ethylene gas for the indicated amount of time. Western blotting using an anti-H⁺-ATPase antibody was used as a lane loading control.