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In vitro and in vivo evidence for actin association of the naphthylphthalamic acid-binding protein from zucchini hypocotylsThe N-1-naphthylphthalamic acid (NPA)-binding protein is part of the auxin efflux carrier, the protein complex that controls polar auxin transport in plant tissues. This study tested the hypothesis that the NPA-binding protein (NBP) is associated with the actin cytoskeleton in vitro and that an intact actin cytoskeleton is required for polar auxin transport in vivo. Cytoskeletal polymerization was altered in extracts of zucchini hypocotyls with reagents that stabilized either the polymeric or monomeric forms of actin or tubulin. Phalloidin treatment altered actin polymerization, as demonstrated by immunoblot analyses following native and denaturing electrophoresis. Phalloidin increased both filamentous actin (F-actin) and NPA-binding activity, while cytochalasin D and Tris decreased both F-actin and NPA-binding activity in cytoskeletal pellets. The microtubule stabilizing drug taxol increased pelletable tubulin, but did not alter either the amount of pelletable actin or NPA-binding activity. Treatment of etiolated zucchini hypocotyls with cytochalasin D decreased the amount of auxin transport and its regulation by NPA. These experimental results are consistent with an in vitro actin cytoskeletal association of the NPA-binding protein and with the requirement of an intact actin cytoskeleton for maximal polar auxin transport in vivo.
Document ID
Document Type
Reprint (Version printed in journal)
Butler, J. H. (Wake Forest University, Department of Biology Winston-Salem, NC 27109, United States)
Hu, S.
Brady, S. R.
Dixon, M. W.
Muday, G. K.
Date Acquired
August 21, 2013
Publication Date
February 1, 1998
Publication Information
Publication: The Plant journal : for cell and molecular biology
Volume: 13
Issue: 3
ISSN: 0960-7412
Subject Category
Life Sciences (General)
Funding Number(s)
Distribution Limits
Non-NASA Center
NASA Discipline Plant Biology