PT  - JOURNAL ARTICLE
AU  - Briskin, D. P.
AU  - Gawienowski, M. C.
TI  - Role of the Plasma Membrane H+-ATPase in K+ Transport
AID  - 10.1104/pp.111.4.1199
DP  - 1996 Aug 01
TA  - Plant Physiology
PG  - 1199--1207
VI  - 111
IP  - 4
4099  - http://www.plantphysiol.org/content/111/4/1199.short
4100  - http://www.plantphysiol.org/content/111/4/1199.full
SO  - Plant Physiol.1996 Aug 01; 111
AB  - The role of the plant plasma membrane H+-ATPase in K+ uptake was examined using red beet (Beta vulgaris L.) plasma membrane vesicles and a partially purified preparation of the red beet plasma membrane H+-ATPase reconstituted in proteoliposomes and planar bilayers. For plasma membrane vesicles, ATP-dependent K+ efflux was only partially inhibited by 100 [mu]M vanadate or 10 [mu]M carbonyl cyanide-p-trifluoromethoxyphenylhydrazone. However, full inhibition of ATP-dependent K+ efflux by these reagents occurred when the red beet plasma membrane H+-ATPase was partially purified and reconstituted in proteoliposomes. When reconstituted in a planar bilayer membrane, the current/voltage relationship for the plasma membrane H+-ATPase showed little effect of K+ gradients imposed across the bilayer membrane. When taken together, the results of this study demonstrate that the plant plasma membrane H+-ATPase does not mediate direct K+ transport chemically linked to ATP hydrolysis. Rather, this enzyme provides a driving force for cellular K+ uptake by secondary mechanisms, such as K+ channels or H+/K+ symporters. Although the presence of a small, protonophore-insensitive component of ATP-dependent K+ transport in a plasma membrane fraction might be mediated by an ATP-activated K+ channel, the possibility of direct K+ transport by other ATPases (i.e. K+-ATPases) associated with either the plasma membrane or other cellular membranes cannot be ruled out.