Figure 4.

Translocation and processing of pre-hsp70 _long::gMDH by isolated proplastids from 3-day-old watermelon cotyledons and protection of the imported gMDH from proteolytic degradation by trypsin (lane 1–3). The ³⁵S-labeled in vitro translation product was incubated for 15 min at 25°C with isolated proplastids (lanes 2 and 3) or with import medium alone (lane 1). Subsequently the import assay was treated with trypsin (10 μg ml⁻¹; lane 3) or with buffer as a control for 5 min on ice (lanes 1 and 2). The same assay was carried out with pre-hsp70_short::gMDH (lanes 7–9) and pre-gMDH (lanes 4–6) as a control. The proteins were analyzed by SDS/PAGE and fluorography.