Yeast-one-hybrid baits, F group bZIP gene expression, and EMSA with bZIP19 and bZIP23. (A) Schematic diagram of the bait fragments (A-G) used to construct the reporter vectors in the yeast-one-hybrid assay. The gray box represents a 10-bp palindromic motif. (B) Relative transcript levels (RTL) of bZIP19, bZIP23, and bZIP24 in 3-week-old Arabidopsis seedlings grown in MS medium, without (Zn-), with 30 μM (Zn+) or with 300 μM ZnSO4 (Zn++) (mean ± SEM). (C) EMSA show that in vitro translated bZIP19 and bZIP23 protein can specifically bind to three tandem repeats of the 10-bp palindromic motif (3Z; 3 x ZDRE; lanes 3 and 7), corresponding to bait G in A, and to two tandem repeats (2Z; lanes 7 and 8), causing the bound fragments to migrate slower through the gel (*) than the labeled free probes found at the bottom of the gel. The observed shift (*) does not occur when using a three-tandem-repeat fragment of a mutated element (3mZ; lanes 2 and 6). A control assay, in which the empty vector was used for in vitro translation, does not show the band shift (lanes 1 and 5), indicating specific binding of bZIP19 and bZIP23 to the ZDRE probes.