Figure 2.

Toc33 targets to chloroplasts efficiently and selectively under a wide range of cytosolic conditions. (A) Radio-labeled Toc33 protein derived from RNCs was incubated in a competitive targeting assay with chloroplasts (CP) and ER, with the addition of cytosolic components as indicated; control is buffer only, WGE is wheat germ extract, chaperones (Hsp) are indicated by their numbers (70/40 or 90), and AP represents apyrase treatment. Membranes were refractionated and washed with carbonate prior to analysis by SDS-PAGE. 10% of protein input is shown, and the protein molecular weight markers are indicated in kDa. (B) Quantification of protein import in part A. Mean and standard error are shown, normalized to the control import into chloroplasts (n = 3), and significant difference from the control import is indicated by one star (p = 0.05) or two stars (p = 0.01). (C) Competitive targeting assay for Toc33 import into chloroplasts (CP) and mitochondria (MT), conducted as described in part A. (D) Quantification of protein import in part C. Mean and standard error are shown, normalized to the control import into chloroplasts (n = 3), and significant difference from the control import is indicated by one star (p = 0.05) or two stars (p = 0.01). (E) Competitive targeting assay for Arabidopsis Sec61β import into ER and chloroplasts (CP), and for At3g58 import into mitochondria (MT) and chloroplasts (CP), conducted as described in part A.