GNOM and Auxin Transport

                                     gnom Phenotype is Mimicked
                                 by Alteration of Auxin Homeostasis



                                  GNOM Encodes a Homolog of Yeast
                                   ARF G-protein Exchange Factors

                                       GNOM Has BFA Sensitive
                                  GDP/GTP Exchange Activity on ARF

                                Small GTPases – Universal Switchers

                                         Secretory pathway



                                        PIN Proteins Cycling

                                     PIN1 Subcellular Movement





                                      What Are the Effects of
                                    Auxin Transport Inhibitors?

                                  PIN1 Exocytosis is Disrupted by
                                     Auxin Transport Inhibitors



                                   Plasma Membrane ATPase Cycling
                                         is Blocked by TIBA





































                                      Dynamic Movement of PIN1



                                     Regulation of PIN Polarity





                                       Role of PINOID Kinase
                                       in PIN Polar Targeting

                                   PINOID kinase loss-of-function
                                       > basal PIN targeting

                                     Role of PID in Controlling
                               PIN Polarity > Auxin Flow > Patterning

                                              TROPISMS

                                   Asymmetric Auxin Distribution
                                         Underlies Tropisms

                                       AtPIN3 Gene and Atpin3
                                         Knock-Out Mutants

                                          Atpin3 Tropisms

                                  Atpin3 Hypocotyl and Apical Hook

                                      AtPIN3::GUS Transgenics

                                        AtPIN3 in Hypocotyl

                                    AtPIN3 in Inflorescence Axis

                                   PIN3 – Lateral Auxin Transport

                                      PIN2 – Root Gravitropism

                                    PIN3 Actin Dependent Cycling

                                PIN3 Immunogold Electron Microscopy

                                         Root Gravitropism

                               Relocation of PIN3 during Gravitropism

                                    Model for Root Gravitropism