Effects of G-protein probes on interactions between auxin efflux carriers and phytotropin receptors in zucchini (Cucurbita pepo L.) microsomal membranes |
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Authors: | Wilkinson S Morris D A |
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Institution: | (1) School of Biological Sciences, University of Southampton, Biomedical Sciences Building, Bassett Crescent East, SO9 3TU Southampton, UK |
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Abstract: | Microsomal vesicles prepared from etiolated hypocotyl tissue of zucchini (Cucurbita pepo L. cv. All Green Bush) exhibited saturable N-1-naphthylphthalamic acid (3H]NPA) binding, NPA-stimulated association of indol-3yl-acetic acid (3H]IAA), and saturable binding of guanosine 5 -O-3-thiotriphosphate] (GTP- -35S]). These vesicles were used to test the possibility that NPA receptors might interact with IAA-anion efflux carriers by coupling through a GTP-binding protein (G-protein). Unlabelled GTP- -S or guanosine 5 -O-2-thiodiphosphate] (GDP- -S) had no effect on saturable NPA binding or on the NPA-stimulated association of IAA with microsomes. NPA did not affect saturable binding of GTP- -35S] to microsomes, either in the presence or absence of saturating concentrations of unlabelled GTP- -S or GDP. It is concluded that the occupancy of phytotropin receptors is not transduced to auxin efflux carriers by a GTP-binding protein. |
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Keywords: | auxin efflux carriers Cucurbita pepo L GTP-binding proteins phytotropin receptors |
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