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Detection of small GTP-binding proteins in the outer envelope membrane of pea chloroplasts
Y Sasaki1, K Sekiguchi, Y Nagano
1Department of Food Science and Technology, Faculty of Agriculture, Kyoto University, Japan.
Abstract:
We found small GTP-binding proteins in the outer envelope membrane of pea chloroplasts. The proteins in this membrane were separated by SDS-PAGE, transferred to a nitrocellulose filter, and incubated with [alpha-32P]GTP. Three GTP-binding proteins with the molecular weight of 24,000 were found. Binding was prevented by 10(-8)-10(-7) M GTP or by 10(-7) M guanosine 5'-[gamma-thio]triphosphate or GDP; binding was unaffected by 10(-8)-10(-6) M ATP. Thermolysin treatment of intact chloroplasts resulted in the loss of GTP-binding activity, suggesting that these proteins were in the cytosolic side of the outer envelope membrane.