Keywords: potassium, plants, flux, cycling, high-affinity transport system (HATS), low-affinity transport system (LATS), membrane potential, cytosol, regulation, toxicity.
Potassium (K+ ) is the most abundant ion in the plant cell, and is required for a wide array of functions, ranging from the maintenance of electrical potential gradients across cell membranes, to the generation of turgor, to the activation of numerous enzymes. The majority of these functions depends more or less directly upon the activities and regulation of membrane-bound K+ transport proteins, operating over a wide range of K+ concentrations. Here, we review the physiological aspects of potassium transport systems in the plasma membrane, re-examining fundamental problems in the field such as the distinctions between high- and low-affinity transport systems, the regulation of cellular K+ pools, and the generation of electrical potentials, placing these discussions in the context of recent discoveries in the molecular biology of K+ transport.
Dev T Britto and Herbert J Kronzucker, University of Toronto, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada.
24 pages, 3 figures, 1 table, 152 references.