Abstract

The presence of an adenylate translocator in the envelope membranes of proplastids isolated from the cultured cells of tobacco (Nicotiana tabacum L. cv. BY2) was examined by means of transport experiments using the silicone oil filtering centrifugation technique. It was observed that proplastids can import [3H]ATP, [3H]ADP, [3H]AMP and less specifically ADP-[14C]Glc which can eventually be used for starch biosynthesis. The effects of specific inhibitors of the mitochondrial adenylate translocator, i.e. atractyloside, bongkrekic acid and carboxyatractyloside were tested. Similar to the case of amyloplasts isolated from the cultured cells of sycamore and chloroplasts isolated from spinach leaves, only ATP and ADP-Glc uptake were shown to be partially inhibited by carboxyatractyloside. On the other hand, neither atractyloside nor bongkrekic acid exerted a significant inhibitory effect on adenylate uptake.

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