FIGURE 3.

The mitochondrial precursor protein prAOX was not imported into isolated leucoplasts. Isolated leucoplasts (113.67 μg) were incubated with in vitro-translated [³⁵S]Met-prAOX, [³⁵S]Met-prRBCS, or [³⁵S]Met-prTic40 under import conditions for 25 min. After import, the leucoplasts were treated with 0.2 mg/mL thermolysin for 30 min on ice, and intact leucoplasts were re-isolated and analyzed by SDS-PAGE. 4% of the plastids in each import reaction were loaded. The gels were stained with Coomassie blue and dried for fluorography. Tr, 1% equivalent of the in vitro-translated proteins used in each import reaction. Leu, leucoplasts; pr, precursor form; int, imported intermediate form; m, imported mature form.