Plant 14-3-3 proteins assist ion channels and pumps.
Turgor pressure is a cellular parameter, important for a range of physiological processes in plants, like cell elongation, gas exchange and gravitropic/phototropic bending. Regulation of turgor pressure involves ion and water transport at the expense of metabolic energy (ATP). The primary pump in the plasma membrane (the H(+)-ATPase) is a key player in turgor regulation since it provides the driving force for ion uptake, followed by water influx through osmosis. Using the phytotoxin fusicoccin (a well-known activator of the ATPase) as a tool, 14-3-3 proteins were identified as regulators of the H(+)-ATPase. Since fusicoccin has a dramatic effect on K(+) accumulation and cellular respiration as well, we studied whether 14-3-3 proteins play a role in the regulation of the mitochondrial F(0)F(1)-ATP synthase and ion channels in the vacuolar and plasma membranes. Besides the plasma membrane H(+)-ATPase, we have identified thus far at least four other transport proteins that are regulated by 14-3-3 proteins. The mechanism of regulation will be described and the possibility that 14-3-3 proteins act as coordinators of ion transporters with varied but interdependent functions will be discussed.
Vrije Universiteit, Faculty of Earth and Life Sciences, Department of Developmental Genetics, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands. ahdeboer@bio.vu.nl
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D048948:14-3-3 Proteins; D000818:Animals; D002462:Cell Membrane / Q000502:physiology; D002736:Chloroplasts / Q000201:enzymology; D007473:Ion Channels / Q000502:physiology*; D016623:Ion Pumps / Q000502:physiology; D008928:Mitochondria / Q000201:enzymology; D018521:Plant Physiological Phenomena; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D048948:14-3-3 Proteins; D007473:Ion Channels; D016623:Ion Pumps; D014446:Tyrosine 3-Monooxygenase