Article thumbnail
Location of Repository

The binding of auxin to the Arabidopsis auxin influxtransporter, AUX1

By David J. Carrier, Norliza Tendot Abu Bakar, Ranjan Swarup, Richard Callaghan, R. (Richard) Napier, Malcolm J. Bennett and Ian D. Kerr


The cellular import of the hormone auxin is a fundamental requirement for the generation of auxin gradients which control a multitude of plant developmental processes. The AUX/LAX family of auxin importers, exemplified by AUX1 from Arabidopsis thaliana, has been shown to mediate auxin import when expressed heterologously. The quantitative nature of the interaction between AUX1 and its transport substrate indole-3-acetic acid (IAA) is incompletely understood and we sought to address this in the present investigation. We expressed AUX1 to high levels in a baculovirus expression system and prepared membrane fragments from baculovirus-infected insect cells. These membranes proved suitable for determination of the binding of IAA to AUX1 and enabled us to determine a Kd of 2.6 µM, comparable with estimates for the Km for IAA transport. The efficacy of a number of auxin analogues and auxin transport inhibitors to displace IAA binding from AUX1 has also been determined and can be rationalized in terms of their physiological effects. Determination of the parameters describing the initial interaction between a plant transporter and its hormone ligand provides novel quantitative data for modelling auxin fluxes

Topics: QK, QH
Publisher: American Society of Plant Biologists
Year: 2008
DOI identifier: 10.1104/pp.108.122044
OAI identifier:
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • (external link)
  • Suggested articles

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.