Fructose-2,6-Bisphosphate as a Regulatory Molecule in Plants

THE ENZYMES THAT SYNTHESIZE AND DEGRADE FRU2,6BISP ... . ... .. . . . . . . . . 1 54 Presence and Location.. . . . . . . . . . ......... . . . . . . . . . . . .. . .. ...... . . . . . . . . . . . . . . .. .. . . 1 55 Regulation by Metabolites ... . . . . . . . . . . . . . .. .. ........ . . .. .. . . . . . . . . ...... . . 155 REGULATION OF THE FRU2,6BISP CONCENTRATION IN VIVO: WHA T INFORMATION IS THE SIGNAL METABOLITE TRANSMITIING? . 158 Authentication of In Vivo Metabolite Measuremellts 1 58 Fru2.6bisP is a Signal for the Ratio of 3-Carbon Phosphorylated Intermediates:Pi.... . . . . . . . . . . . . . . . . . . 159 Rising Fru2.6bisP Signals whell HexosePhosphates are Accumulating 160 Further Possible Mechanisms to Regulate the Fru2.6bisP concentration 161 THE TARGETS: IN VITRO EFFECT ON THE ENZYMES . . . . ..... . . . ..... . . . . . . . . .... . .. 162 The Cytosolic Frul ,6Pase..... . . . . . . . . . . . . ......... . . . . . . . . . . . . . . . .. .. ... . . . . . . . . . 163 PFP 163 THE TARGETS: IN VIVO IMPACT OF FRU2,6BISP ON FLUXES . ... . . . . . . . . . . .. .... 168 Role of the Cytosolic Frul,6Pase in the Control of Sucrose Synthesis 169 011 the Role of PFP in Plant Metabolism 173