Heterogeneity of auxin-accumulating membrane vesicles from Cucurbita and Zea: a possible reflection of cell polarity |
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Authors: | Martin Lützelschwab Han Asard Ulrike Ingold Rainer Hertel |
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Affiliation: | (1) Institut für Biologie III der Universität, Schänzlestrasse 1, D-7800 Freiburg i.Br., Federal Republic of Germany;(2) Department of General Biology, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium |
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Abstract: | When microsomes from hypocotyls of Cucurbita pepo L. or coleoptiles of Zea mays L. were centrifuged on dextran-sucrose gradients a heterogeneity of auxin-accumulating vesicles was observed. Vesicles from the top part of the gradient showed saturable, specific accumulation of indole-3-acetic acid with only a small stimulation by phytotropins, and with very few binding sites for 1-N-naphthylphthalamic acid. In the vesicles from the lower part of the gradient, net accumulation of indole-3-acetic acid could be strongly increased by addition of phytotropins; binding of 1-N-naphthylphthalamic acid was high in this region. After two-phase partitioning, both kinds of vesicles were found in the upper-phase membrane fraction considered to be purified plasma membrane. The hypothesis is discussed that vesicles can be separated from the apical and basal parts of the cell's plasmalemma.Abbreviations CCO cytochrome-c oxidase - CCR KCN-insensitive NADH-dependent cytochrome-c reductase - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - IDPase inosine 5-diphosphatase - ION3 ionophore mixture of carbonylcyanide-3-chlorophenylhydrazone, nigericin and valinomycin - 1-NAA 1-naphthaleneacetic acid - NPA 1-N-naphthylphthalamic acid - PBA 2-(1-pyrenoyl)benzoic acid - UDPG uridine diphosphoglucose |
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Keywords: | Auxin transport Cucurbita (auxin transport) Membrane vesicle Polarity (auxin transport) Zea (auxin transport) |
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