Reconstitution of an electrogenic auxin transport activity mediated by Arabidopsis thaliana plasma membrane proteins.
Plasma membrane proteins from Arabidopsis thaliana leaves were reconstituted into proteoliposomes and a K+ diffusion potential was generated. The resulting ionic fluxes, determined in the presence of the plant hormone auxin (indole-3 acetic acid), showed an additional electrogenic and saturable component, with a K(M) of 6 microM. This flux was neither detected in liposomes in the presence of indole-3 acetic acid, nor in proteoliposomes in the presence of an inactive auxin analog and was completely inhibited by 3 microM naphtylphthalamic acid, a specific inhibitor of the auxin efflux carrier. The efficiency of the reconstituted carrier and the mechanism of its regulation by naphtylphthalamic acid are discussed.
Szponarski
W
W
Biochimie et Physiologie Moléculaire des Plantes, INRA/ENSA-M/CNRS URA 2133, Montpellier, France. szponarski@ensam.inra.fr
Guibal
O
O
Espuna
M
M
Doumas
P
P
Rossignol
M
M
Gibrat
R
R
D017360:Arabidopsis / Q000378:metabolism* / Q000648:ultrastructure; D001692:Biological Transport; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000378:metabolism*; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism
D007210:Indoleacetic Acids; D008565:Membrane Proteins; D010940:Plant Proteins