A new perspective on auxin perception.
An important question in modern plant biology concerns the mechanisms of auxin perception. Despite the recently discovered soluble receptor, the F-box protein TIR1, there is no doubt that another type of signal perception exists, and is linked to the plasma membrane. Two models for the receptor have been suggested: either the receptor includes a protein kinase, or it is coupled with a G-protein. We propose a third model, acting through Ca(2+)-channels in the plasma membrane. The model is based on the revealed rapid auxin-induced reactions, including changes in the membrane potential, shifts in cytosol concentration of Ca(2+) and H(+) and modulation of cell sensitivity to hormones by the external Ca(2+) concentration. Detailed inhibitor analysis with both living cells and isolated plasma membranes show that auxin might directly stimulate Ca(2+) transport through the plasma membrane. A hypothetical scheme of auxin perception at the plasma membrane is suggested together with further transduction events. In addition, comparative analyses of auxin and serotonin perceptions are provided.
Shishova
Maria
M
Department of Plant Physiology and Biochemistry, St. Petersburg State University, 199034 St. Petersburg, Russia. mshishova@mail.ru
Lindberg
Sylvia
S
D002118:Calcium / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects* / Q000235:genetics; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008954:Models, Biological; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics
D007210:Indoleacetic Acids; D010940:Plant Proteins; D002118:Calcium