Permeation of Ca2+ through K+ channels in the plasma membrane of Vicia faba guard cells

1992 ◽  
Vol 128 (2) ◽  
Author(s):  
K.A. Fairley-Grenot ◽  
S.M. Assmann
Keyword(s):  
Plasma Membrane ◽  
Vicia Faba ◽  
Guard Cells ◽  
K Channels

scholarly journals K+ transport properties of K+ channels in the plasma membrane of Vicia faba guard cells.

1988 ◽  
Vol 92 (5) ◽  
pp. 667-683 ◽  
Author(s):  
J I Schroeder
Keyword(s):  
Plasma Membrane ◽  
Transport Properties ◽  
Vicia Faba ◽  
Guard Cell ◽  
Guard Cells ◽  
Stomatal Opening ◽  
Whole Cell ◽  
K Channels ◽  
K Transport ◽  
K Currents

Electrical properties of the plasma membrane of guard cell protoplasts isolated from stomates of Vicia faba leaves were studied by application of the whole-cell configuration of the patch-clamp technique. The two types of K+ currents that have recently been identified in guard cells may allow efflux of K+ during stomatal closing, and uptake of K+ during stomatal opening (Schroeder et al., 1987). A detailed characterization of ion transport properties of the inward-rectifying (IK+,in) and the outward-rectifying (IK+,out) K+ conductance is presented here. The permeability ratios of IK+,in and IK+,out currents for K+ over monovalent alkali metal ions were determined. The resulting permeability sequences (PK+ greater than PRb+ greater than PNa+ greater than PLi+ much greater than PCs+) corresponded closely to the ion specificity of guard cell movements in V. faba. Neither K+ currents exhibited significant inactivation when K+ channels were activated for prolonged periods (greater than 10 min). The absence of inactivation may permit long durations of K+ fluxes, which occur during guard cell movements. Activation potentials of inward K+ currents were not shifted when external K+ concentrations were changed. This differs strongly from the behavior of inward-rectifying K+ channels in animal tissue. Blue light and fusicoccin induce hyperpolarization by stimulation of an electrogenic pump. From slow-whole-cell recordings it was concluded that electrogenic pumps require cytoplasmic substrates for full activation and that the magnitude of the pump current is sufficient to drive K+ uptake through IK+,in channels. First, direct evidence was gained for the hypothesis that IK+,in channels are a molecular pathway for K+ accumulation by the finding that IK+,in was blocked by Al3+ ions, which are known to inhibit stomatal opening but not closing. The results presented in this study strongly support a prominent role for IK+,in and IK+,out channels in K+ transport across the plasma membrane of guard cells.

Extracellular Ca2+ Regulating Stomatal Movement and Plasma Membrane K+ Channels in Guard Cells of Vicia faba Under Salt Stress

2008 ◽  
Vol 34 (11) ◽  
pp. 1970-1976 ◽  
Author(s):  
Xiang ZHAO ◽  
Yan-Liang WANG ◽  
Ya-Jing WANG ◽  
Xi-Li WANG ◽  
Xiao ZHANG
Keyword(s):  
Plasma Membrane ◽  
Salt Stress ◽  
Vicia Faba ◽  
Guard Cells ◽  
Stomatal Movement ◽  
K Channels

scholarly journals Two Plasma Membrane H+-ATPase Genes Expressed in Guard Cells of Vicia faba Are Also Expressed Throughout the Plant

1996 ◽  
Vol 37 (5) ◽  
pp. 650-659 ◽  
Author(s):  
A. E. Hentzen ◽  
L. B. Smart ◽  
L. E. Whimmers ◽  
H. H. Fang ◽  
J. I. Schroeder ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Vicia Faba ◽  
Guard Cells

scholarly journals External pH effects on the depolarization-activated K channels in guard cell protoplasts of Vicia faba.

1994 ◽  
Vol 103 (5) ◽  
pp. 807-831 ◽  
Author(s):  
N Ilan ◽  
A Schwartz ◽  
N Moran
Keyword(s):  
Plasma Membrane ◽  
Surface Charge ◽  
Vicia Faba ◽  
Guard Cell ◽  
Voltage Dependence ◽  
Single Channel ◽  
Ph Effects ◽  
Homogeneous Surface ◽  
K Channels ◽  
Guard Cell Protoplasts

Previous studies reveal that the pH of the apoplastic solution in the guard cell walls may vary between 7.2 and 5.1 in closed and open stomata, respectively. During these aperture and pH changes, massive K+ fluxes cross the cellular plasma membrane driving the osmotic turgor and volume changes of guard cells. Therefore, we examined the effect of extracellular pH on the depolarization-activated K channels (KD channels), which constitute the K+ efflux pathway, in the plasma membrane of Vicia faba guard cell protoplasts. We used patch clamp, both in whole cells as well as in excised outside-out membrane patches. Approximately 500 KD channels, at least, could be activated by depolarization in one protoplast (density: approximately 0.6 micron-2). Acidification from ph 8.1 to 4.4 decreased markedly the whole-cell conductance, GK, of the KD channels, shifted its voltage dependence, GK-EM, to the right on the voltage axis, slowed the rate of activation and increased the rate of deactivation, whereas the single channel conductance was not affected significantly. Based on the GK-EM shifts, the estimated average negative surface charge spacing near the KD channel is 39 A. To quantify the effects of protons on the rates of transitions between the hypothesized conformational states of the channels, we fitted the experimental macroscopic steady state conductance-voltage relationship and the voltage dependence of time constants of activation and deactivation, simultaneously, with a sequential three-state model CCO. In terms of this model, protonation affects the voltage-dependent properties via a decrease in localized, rather than homogeneous, surface charge sensed by the gating moieties. In terms of either the CO or CCO model, the protonation of a site with a pKa of 4.8 decreases the voltage-independent number of channels, N, that are available for activation by depolarization.

Isolation of cDNA for a Plasma Membrane H+-ATPase from Guard Cells of Vicia faba L.

1995 ◽  
Vol 36 (5) ◽  
pp. 919-924 ◽  
Author(s):  
Nobuyoshi Nakajima ◽  
Hikaru Saji ◽  
Mitsuko Aono ◽  
Noriaki Kondo
Keyword(s):  
Plasma Membrane ◽  
Vicia Faba ◽  
Guard Cells ◽  
Vicia Faba L

Distinct fluorescent pattern of KAT1::GFP in the plasma membrane of Vicia faba guard cells

2007 ◽  
Vol 86 (8) ◽  
pp. 489-500 ◽  
Author(s):  
Ulrike Homann ◽  
Tobias Meckel ◽  
Jennifer Hewing ◽  
Marc-Thorsten Hütt ◽  
Annette C. Hurst
Keyword(s):  
Plasma Membrane ◽  
Vicia Faba ◽  
Guard Cells ◽  
Fluorescent Pattern

Cytosolic calcium regulates ion channels in the plasma membrane of Vicia faba guard cells

Nature ◽  
1989 ◽  
Vol 338 (6214) ◽  
pp. 427-430 ◽  
Author(s):  
Julian I. Schroeder ◽  
Susumu Hagiwara
Keyword(s):  
Plasma Membrane ◽  
Ion Channels ◽  
Vicia Faba ◽  
Guard Cells ◽  
Cytosolic Calcium
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