1;Transporters and Pumps in Plant Signaling;3 1.1;Preface;5 1.2;Contents;7 1.3;Part I: Membranes and Water Transport;9 1.3.1;Plant Aquaporins: Roles in Water Homeostasis, Nutrition, and Signaling Processes;10 1.3.1.1;1 Introduction;10 1.3.1.2;2 Plant Aquaporins;12 1.3.1.2.1;2.1 Plasma Membrane Intrinsic Proteins;12 1.3.1.2.2;2.2 Tonoplast Intrinsic Proteins;13 1.3.1.2.3;2.3 Small Basic Intrinsic Proteins;14 1.3.1.2.4;2.4 Nodulin26-Like Intrinsic Proteins;16 1.3.1.2.5;2.5 X Intrinsic Proteins;17 1.3.1.2.6;2.6 Hybrid Intrinsic Proteins;17 1.3.1.2.7;2.7 GlpF-Like Intrinsic Proteins;17 1.3.1.3;3 Structural Features of Major Intrinsic Proteins;18 1.3.1.3.1;3.1 Aquaporin Structure;18 1.3.1.3.2;3.2 Aromatic/Arginine (ar/R) Constriction Region;19 1.3.1.3.3;3.3 Oligomer Formation;19 1.3.1.4;4 Why Do Plants Contain So Many MIP Isoforms?;21 1.3.1.4.1;4.1 MIP Function Related to Water Transport;22 1.3.1.4.2;4.2 MIP Function Related to Nitric Oxide Transport;23 1.3.1.4.3;4.3 MIP Function Related to Ammonia Transport;24 1.3.1.4.4;4.4 MIP Function Related to Urea Transport;25 1.3.1.4.5;4.5 MIP Function Related to Carbon Dioxide Transport;26 1.3.1.4.6;4.6 MIP Function Related to Hydrogen Peroxide Transport;27 1.3.1.4.7;4.7 MIP Function Related to Organic Acid Transport;28 1.3.1.4.8;4.8 MIP Function Related to Glycerol Transport;29 1.3.1.4.9;4.9 MIP Function Related to Boric Acid Transport;30 1.3.1.4.10;4.10 MIP Function Related to Silicic Acid Transport;31 1.3.1.4.11;4.11 MIP Function Related to Arsenite/Antimonite Transport;31 1.3.1.5;5 Conclusion;33 1.3.1.6;References;33 1.4;Part II: Signaling Related to Ion Transport;44 1.4.1;Plant Proton Pumps: Regulatory Circuits Involving H+-ATPase and H+-PPase;45 1.4.1.1;1 P-Type H+-ATPases;45 1.4.1.1.1;1.1 Arabidopsis Encodes 11 Members of H+-ATPases;46 1.4.1.1.2;1.2 Mechanism of Activation by 14-3-3 Proteins;47 1.4.1.1.3;1.3 Phosphoproteomic Studies of Plasma Membrane H+-ATPases;48 1.4.1.1.4;1.4 Controlling the Size of the Stomatal Pore;49 1.4.1.1.4.1;1.4.1 Opening of Guard Cells;49 1.4.1.1.4.2;1.4.2 Closure of Guard Cells;50 1.4.1.1.4.3;1.4.3 Pathogens Modulate the H+ Pumps to Invade Plants Through the Stomatal Pore;50 1.4.1.1.5;1.5 PKS5: A Protein Kinase Preventing Binding of 14-3-3 Protein;51 1.4.1.1.5.1;1.5.1 ScaBP1: A Calcium Binding Protein Modulating PKS5 Action;51 1.4.1.1.5.2;1.5.2 DnaJ: A Chaperone Like Protein Repressing PKS5 Activity;52 1.4.1.1.6;1.6 Nutrient Uptake and Responses to Changes in the Soil;52 1.4.1.1.6.1;1.6.1 Response to Limited Phosphate;53 1.4.1.2;2 Plant H+-PPases;53 1.4.1.2.1;2.1 Vacuolar H+-PPases in Fruits;55 1.4.1.2.2;2.2 Vacuolar H+-PPase Is a Key Player for Plant Salt Tolerance;56 1.4.1.2.3;2.3 Vacuolar H+-PPases in Maize Aleurone;56 1.4.1.2.4;2.4 Subcellular Localization of Plant H+-PPases;57 1.4.1.2.5;2.5 Are There Other H+-PPases in Plants?;58 1.4.1.2.6;2.6 Transcriptional Regulation of H+-PPases;58 1.4.1.2.6.1;2.6.1 Sugar Starvation;59 1.4.1.2.6.2;2.6.2 Pi Starvation;60 1.4.1.2.7;2.7 Puzzling Phenotypes Triggered by Altering the Expression of H+-PPases in Plants;60 1.4.1.2.8;2.8 Could the H+-PPase Affect Sucrose Phloem Loading?;61 1.4.1.2.8.1;2.8.1 PPi Concentrations Are Essential for Sucrose Phloem Loading;61 1.4.1.2.8.2;2.8.2 H+-PPase and H+-ATPase Localize in Close Proximity at the PM of Sieve Elements;61 1.4.1.2.8.3;2.8.3 Hypothetical Model;62 1.4.1.3;References;63 1.4.2;Na+ and K+ Transporters in Plant Signaling;71 1.4.2.1;1 Introduction;72 1.4.2.2;2 K+ Transport;72 1.4.2.2.1;2.1 K+ Uptake from Diluted Solutions and Plant Signaling;73 1.4.2.2.2;2.2 Transcriptional Regulation of High-Affinity HAK Transporters;74 1.4.2.2.3;2.3 Regulation of AKT1 Channels by Phosphorylation/Dephosphorylation;78 1.4.2.3;3 Sodium Transport;80 1.4.2.3.1;3.1 Sodium Influx at the Plasma Membrane;80 1.4.2.3.2;3.2 Sodium Efflux and Long-Distance Transport; the SOS System85 1.4.2.3.3;3.3 Transport at the Tonoplast for Na+ Sequestration;91 1.4.2.4;4 Concluding Remarks;94 1.4.2.5;Referen