Journal article

Rapid, futile K cycling and pool-size dynamics define low-affinity potassium transport in barley

Mark W Szczerba, Dev T Britto, Herbert J Kronzucker

PLANT PHYSIOLOGY | AMER SOC PLANT BIOLOGISTS | Published : 2006

Abstract

Using the short-lived radiotracer 42K+, we present a comprehensive subcellular flux analysis of low-affinity K+ transport in plants. We overturn the paradigm of cytosolic K+ pool-size homeostasis and demonstrate that low-affinity K+ transport is characterized by futile cycling of K+ at the plasma membrane. Using two methods of compartmental analysis in intact seedlings of barley (Hordeum vulgare L. cv Klondike), we present data for steady-state unidirectional influx, efflux, net flux, cytosolic pool size, and exchange kinetics, and show that, with increasing external [K+] ([K+]ext), both influx and efflux increase dramatically, and that the ratio of efflux to influx exceeds 70% at [K+]ext > ..

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University of Melbourne Researchers