1992 Fiscal Year Final Research Report Summary
Identification and isolation of pyruvate translocator protein of the envelope membranes of C_4 mesophyll chloroplasts.
| Project/Area Number |
03640564
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
植物生理学
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| Research Institution | Saitama University |
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Principal Investigator |
OHNISHI Jun-ichi Saitama University, Faculty of Science, Ass. Professor, 理学部, 助教授 (40143242)
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| Project Period (FY) |
1991 – 1992
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| Keywords | C_4 plants / Sorghum bicolor / Mesophyll cells / Chloroplasts / Envelope membranes / Pyruvate / Translocator / NBD-C1 |
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| Research Abstract |
A) A comparative study of the plausible mechanism of pyruvate transport into mesophyll chloroplasts, i.e., either Na^+- or H^+- cotransport, was invesitigated in many C_4 species from both dicots and monocots (Gramineae). Light enhancement of pyruvate transport was mimicked in the dark by a H^+-jump only in Andropogeneae and Arundinelleae (12 species) and by a Na^+ jump in all the other species tested (21 species). The result together with our earlier demonstration of Na^+/pyruvate cotransport in a few C_4 species suggests that pyruvate is cotransported either with Na^+ or H^+ depending on C_4 species.
B) The above inferred mechanism of pyruvate transport, H^+/pyruvate cotransport into mesophyll chloroplasts of limited C_4 species was tested by measuring the medium pH change on pyruvate addition in Sorghum and Coix. A good 1 to 1 correlation of the initial rates of pyruvate uptake and H^+ uptake was established, even when pyruvate transport was partially inhibited by NEM or NBD-C1.
C) By incubating Sorghum mesophyll chloroplasts with [^<14>C]NBD-C1 with and without pyruvate or a pyruvate analogue (a cinnamic acid derivative), a peptide band was differentially labelled suggesting the protection from the labelling by substrate. This band was tentatively identified as pyruvate translocator, and is presently being purified.
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