title: Plant cation/H+ exchangers (CAXs): biological functions and genetic manipulations.
abstract: Inorganic cations play decisive roles in many cellular and physiological processes and are essential components of plant nutrition. Therefore, the uptake of cations and their redistribution must be precisely controlled. Vacuolar antiporters are important elements in mediating the intracellular sequestration of these cations. These antiporters are energized by the proton gradient across the vacuolar membrane and allow the rapid transport of cations into the vacuole. CAXs (for CAtion eXchanger) are members of a multigene family and appear to predominately reside on vacuoles. Defining CAX regulation and substrate specificity have been aided by utilising yeast as an experimental tool. Studies in plants suggest CAXs regulate apoplastic Ca(2+) levels in order to optimise cell wall expansion, photosynthesis, transpiration and plant productivity. CAX studies provide the basis for making designer transporters that have been used to develop nutrient enhanced crops and plants for remediating toxic soils.
authors.affiliation: United States Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX 77030, USA
authors.forename: M
authors.initials: M
authors.lastname: Manohar
authors.forename: T
authors.initials: T
authors.lastname: Shigaki
authors.forename: K D
authors.initials: KD
authors.lastname: Hirschi
mesh_terms: D017920:Antiporters / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D002412:Cations / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D007425:Intracellular Membranes / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D017494:Proton Pumps / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D017920:Antiporters; D027682:Cation Transport Proteins; D002412:Cations; D017494:Proton Pumps; D002118:Calcium