Sulfate and sulfite translocation via the phosphate translocator of the inner envelope membrane of chloroplasts |
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Authors: | Rüdiger Hampp Irmgard Ziegler |
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Institution: | (1) Lehrstuhl für Botanik, Technische Universität München, Munchen, Arcisstr. 21, D-8000 München 2, Federal Republic of Germany;(2) Institut für Biochemie der Gesellschaft für Strahlen- und Umweltforschung mbH, Munchen, Arcisstr. 21, D-8000 München 2, Federal Republic of Germany |
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Abstract: | The permeability of the inner envelope membranes of spinach (Spinacia oleracea) chloroplasts to sulfite and sulfate was investigated in vitro, using the technique of silicone oil centrifugal filtration. The results show that there is a permeability towards both ions, resulting in rates of uptake of about 1.0 (SO
3
2-
) and 0.7 (SO
4
2-
) mol mg chlorophyll-1 h-1 respectively (external concentration 2 mmol l-1). The rates depend on the external concentration of the anions. Anion exchange experiments with 35S-preloaded chloroplasts indicate that sulfite and sulfate are exchanged for inorganic phosphate, phosphoglyceric acid, and dihydroxyacetone phosphate with rates up to 14 nmol mg chlorophyll-1 min-1. There is no exchange for glucose-6-phosphate and malate. Because of the similarities to the transport of inorganic phosphate and triose phosphates the results give evidence that the phosphate translocator of the inner envelope membrane of chloroplasts is also involved in sulfite and sulfate transport — at least in part.Abbreviations DHAP
dihydroxyacetone phosphate
- PGA
3-phosphoglycerate
- Pi
inorganic phosphate
- Si
sultite, sulfate |
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Keywords: | Chloroplast envelope Ion transport Sulfate Sulfite |
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