FIGURE 9.

Binding of preSSU to Toc translocons is mediated by both atToc159 and atToc33. A, energy-depleted, in vitro translated [³⁵S]preSSU was incubated with isolated chloroplasts from WT:ppi1, R130A:ppi1, or F67A:ppi1 plants in the absence of energy. The samples were treated with 0.1 mm CuP for 5 min. After the cross-linking reactions were quenched, the chloroplasts were detergent-solubilized, and proteins were immunoprecipitated with anti-atToc159 serum, atToc33 affinity-purified antibodies, or preimmune serum. The immunoprecipitates were analyzed by SDS-PAGE and phosphorimaging to detect co-immunoprecipitated [³⁵S]preSSU or by immunoblotting to detect atToc159 or atToc33.