MED31 is an important component of the SHR/SCR complex. (A) Co-IP assay showing that SHR associates with SCR and MED31 in N. benthamiana. MED31-myc, SCR, and SHR-GFP were coinfiltrated into N. benthamiana leaves. Protein samples were immunoprecipitated with anti-GFP antibody and immunoblotted with anti-myc and anti-SCR antibodies. MED31-myc– and SCR-coinfiltrated N. benthamiana leaves were used as negative controls. (B) In vitro pull-down assays showing that MED31 forms a ternary complex with SHR and SCR. GST-SHR and SCR-FLAG were pulled down by MED31-MBP immobilized on amylose resin. Proteins bound to amylose resin were eluted and analyzed by anti-GST and anti-FLAG antibodies, respectively. (C) In vitro pull-down assays showing that SHR directly interacts with SCR but not itself. SCR-FLAG was pulled down by GST-SHR immobilized on a GST-Bind resin. Protein bound to the GST-Bind resin was eluted and analyzed using an anti-FLAG antibody. (D) In vitro pull-down assay showing that SCR directly interacts with SHR but not itself. SHR-FLAG was pulled down by GST-SCR immobilized on a GST-Bind resin. Protein bound to the GST-Bind resin was eluted and analyzed using an anti-FLAG antibody. CBB, Coomassie brilliant blue staining; MW, molecular weight (mass).