Ferredoxin-NADP(+) reductase, a nuclearly-coded enzyme unaffected by tentoxin treatment.
Previous studies in our laboratory have shown that tentoxin prevents the incorporation of polyphenol oxidase (PPO), a nuclearly-coded protein, into the chloroplasts of sensitive species. In this study, we show, by comparison of electrophoretically separated isozymes, that ferredoxin-NADP(+) reductase (FNR) is nuclearly coded in Nicotiana. Electrophoresis of FNR isozymes from tentoxin treated seedlings of a sensitive and a resistant species demonstrated that, unlike PPO, ferredoxin-NADP(+) reductase was unaffected by tentoxin treatment. These data indicate that tentoxin selectively inhibits transport of cytoplasmically synthesized proteins into the chloroplast, and does not produce a generalized disruption of cellular integration.
Weed Science Lab, USDA-S, 38776, Stoneville, MS.
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Lax
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Vaughn
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Sisson
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Templeton