Figure 4.

IEP110 uses the general import and processing components of chloroplasts. (A) tp110-110N import into pea chloroplasts was assayed in the absence or presence of increasing pSSU concentration. pSSU_ex was synthesized in E. coli and added as a urea-denatured protein to the import assay (final urea concentration 80 mM). Import experiments were initiated by the addition of organelles (equivalent to 30 μg chl). (B) E. coli–synthesized pSSU_ex competes the import of reticulocyte lysate made ³⁵S-labeled pSSU with similar efficiency as tp110-110N. Experimental conditions are as desribed in A. (C) Tp110-110N and pSSU are both processed in vitro by a stromal extract. A stromal processing extract was incubated for either 0 min (lanes 1 and 4) or 90 min (lanes 2, 3 and 5, 6) with the respective translation product in the absence (lane 2 and 5) or presence (lane 3 and 6) of 10 mM 1,10 o-phenanthroline.