Figure 3.
The Twin-Positive and RVSI Motifs Are Specifically Important for prFB Import into Leucoplasts.
(A) The transit-peptide sequences of prFB-M42V and its mutants. The RVSI and twin-positive motifs are denoted in boldface letters and underlined, and the Ala and Glu replacing them in the mutants are colored red. The Val replacing the Met at residue 42 is colored blue.
(B) and (C) Import of prFB-M42V and its mutants into leucoplasts and chloroplasts. [35S]Met preproteins were incubated with isolated leucoplasts (Leu) and chloroplasts (Cpt), respectively, under import conditions for 10 min. Intact plastids were reisolated and analyzed by SDS-PAGE. Import efficiencies were calculated and normalized to those of prFB-M42V. Tr, 20 and 50% input for leucoplasts (B) and chloroplasts (C), respectively. Data shown are means ± sd of four independent experiments.