Cytosolic glutamine synthetase is present in the phloem sap of rice (Oryza sativa L.) |
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| Authors: | Tomohiro TANAKA Nobuo SUZUI Hiroaki HAYASHI Tomoyuki YAMAYA Tadakatsu YONEYAMA |
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| Institution: | Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657 and;Department of Applied Biological Chemistry, Faculty of Agriculture, Tohoku University, Sendai 981-8555, Japan |
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| Abstract: | The presence of glutamine synthetase (GS) in the rice sieve tube was examined. Proteins in the rice phloem sap from leaf sheaths were separated by sodium dodecylsulfate–polyacrylamide gel electrophoresis, transferred to polyvinylidine difluoride membranes and immunoblotted with anti-GS1 antibody. A cross-reacting band, thought to be GS1, was detected in the phloem sap. Moreover, the phloem sap contained a significant amount of GS transferase activity. Previous studies have shown that the concentrations of substrates and cofactors in the rice phloem sap are sufficient for cytosolic GS reaction. These data suggest that physiologically active GS1 is present in rice phloem sap, which might convert glutamate to glutamine in vivo . |
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| Keywords: | glutamine synthetase GS1 nitrogen phloem sap rice (Oryza sativa L ) |
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