Inward-rectifying K+ channels in guard cells provide a mechanism for low-affinity K+ uptake.

Schroeder, Julian I.; Fang, Henry H.

doi:10.1073/pnas.88.24.11583

Cited by 125 publications

(87 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results and previous findings (Schroeder and Fang, 1991) did not lead to the conclusion that high-affinity K + uptake in plants is mediated by passive K+ transport through ion channels, as implied in a recent commentary (Kochian and Lucas, 1993). The results do, however, support biophysical conjectures suggesting that one function of K+i, channels may be to serve as a backup system for high-affinity K + uptake (Schroeder and Fang, 1991), for example, when the plant high-affinity mechanism is genetically or environmentally disabled. In addition, the K+in channel cannot be the high-affinity K+ transporter because the transporter in higher plant cells saturates at -0.2 mM K+, whereas the K+i, channel saturates at >50 mM extracellular K + (Schroeder and Fang, 1991).…”

Section: Letter To the Editorcontrasting

confidence: 48%

“…channels represent a major component of the low-affinity K + uptake mechanism. Biophysical and physiological studies of K+in channels have shown that they are well suited to serve as an efficient mechanism for K + uptake at K+ concentrations >O3 mM with kinetics similar to those of the low-affinity mechanism (Schroeder and Fang, 1991). The driving force for K+in channel-mediated K+ uptake is provided by the negative membrane potential maintained by the protonextruding plasma membrane proton PumP.…”

Section: Physiological Roles Of Inward-rectifying K+ Channelsmentioning

confidence: 99%

“…Schroeder and colleagues (Schroeder et al, 1987;Schroeder and Fang, 1991) have suggested that K+i. channels represent a major component of the low-affinity K + uptake mechanism.…”

Section: Physiological Roles Of Inward-rectifying K+ Channelsmentioning

confidence: 99%

See 2 more Smart Citations

Physiological Roles of Inward-Rectifying K+ Channels.

Gassmann¹,

Ward²,

Schroeder³

1993

Plant Cell

View full text Add to dashboard Cite

Section: Letter To the Editorcontrasting

confidence: 48%

Section: Physiological Roles Of Inward-rectifying K+ Channelsmentioning

confidence: 99%

See 1 more Smart Citation

Physiological Roles of Inward-Rectifying K+ Channels.

Gassmann¹,

Ward²,

Schroeder³

1993

Plant Cell

View full text Add to dashboard Cite

“…In guard cells, relatively little change in the activation voltage was observed when [K' ],,, changed in the range from 10 to 100 mM K+. However, in the range from O to 10 mM K+, the activation voltage does respond to alterations in [K+],,, (Schroeder and Fang, 1991). Similarly, in A. tkaliana root cells the K+,, channel activation voltage always remained 20 to 30 mV negative of E , (Maathuis and Sanders, 1995).…”

Section: K+ Channels Sense K*mentioning

confidence: 99%

“…Additional unequivocal evidence that Kt,,, channels actually do sense the external K+ concentration originates from the observation that these channels no longer open when extracellular K+ is removed (Schroeder and Fang, 1991;Gassmann and Schroeder, 1994;Maathuis and Sanders, 1997 (Schachtman et al, 1992;Cao et al, 1995), after replacement of K+ by Na+ or Li+, large outward K+ currents can be generated by KATl (Cao et al, 1995;Very et al, 1995). Apparently, the Kti, channel sensor also responds to cations of limited permeability such as Li+ and Na+, and further research on its physiological role would be of interest.…”

Section: K+ Channels Sense K*mentioning

confidence: 99%

Roles of Higher Plant K+ Channels

Maathuis¹,

Ichida²,

Sanders³

et al. 1997

Plant Physiology

196

123

View full text Add to dashboard Cite

Living organisms maintain a cellular solute composition very different from that of the externa1 environment. This implicitly requires the transport of solutes across the cell membrane, and ion channels are integral membrane proteins that play indispensable roles in such transport. In the past dozen years, radical advances have aided in our understanding of ion channel function and regulation in higher plants. Nowhere are these advances more striking than with respect to K+ channels, where the synergistic application of electrophysiological, cell biological, physiological, and molecular techniques has demonstrated an array of channel types playing diverse but defined roles in plant physiology.The major function of K+ channels in animal cells is that of membrane voltage control and short-term repolarization of the membrane. Although K+ channels in plants share similar roles in the regulation of the membrane voltage, early research on guard cells led to the model that shows that plant K+ channels in addition provide important pathways for long-term physiological K+ uptake and release. An extensive range of recent studies suggests diverse longterm transport functions of plant K+ channels, including participation in osmotically driven movements, solute loading into the xylem, cation nutrition, and, by virtue of the presence of K+ channels at endomembranes, intracellular solute redistribution and cytosolic volume control. Most plant K+ channels remain activated for long periods of time, which is critica1 for this proposed long-term transport function of K+ channels in plants. Because higher plant K+ channels are proposed to play a role in regulating both the influx and the efflux of K+ from cells, activity of these channels may impinge upon aspects of turgor and water relations of a11 plant cells. In this Update we focus on important principles of plant K+ channel function and on the proposed physiological roles of specific plant K + channel types in the plasma membrane and tonoplast (Fig. 1A) of different plant cells.

show abstract

Predicting effects of cations on copper toxicity to lettuce (Lactuca sativa) by the biotic ligand model

Peijnenburg

Hendriks

et al. 2011

Enviro Toxic and Chemistry

View full text Add to dashboard Cite

A biotic ligand model (BLM) was developed to estimate Cu toxicity to lettuce (Lactuca sativa) in terms of root elongation after 4 d of exposure. Effects of Na(+), K(+), Ca(2+), and Mg(2+) on Cu toxicity were examined. The addition of these cations resulted in a 50-fold difference in the copper median effective activity (EC50 cu2+). However, these variations could not be interpreted entirely as a function of the concentrations of these cations alone. In particular, only the relationship between EC50 cu2+ and the activity of protons was found to be significant in the whole range of pH examined from 5.0 to 7.0. The addition of K(+), Na(+), Ca(2+), and Mg(2+) at concentrations up to 20 mM resulted in a 16-fold difference in EC50 cu2+ values. This difference was significant, as indicated by non-overlapping standard deviations of the negative logarithm of EC50 cu2+ pEC50 cu2+) obtained with (7.37 ± 0.22) and without (6.76 ± 0.22) additions of K(+), Na(+), Ca(2+), and Mg(2+). The variations were not statistically significantly related to concentrations of these cations; therefore, only protons can be integrated in the BLM predicting Cu toxicity to lettuce L. sativa with the important parameters: log K(HBL) =6.27, log K(CuBL) =7.40, and [formula in text]. The lack of significant relationships between EC50 cu2+ and concentrations of the cations was not in line with the main assumption of the BLM about the competition between cations for binding sites.

show abstract

Inward-rectifying K+ channels in guard cells provide a mechanism for low-affinity K+ uptake.

Cited by 125 publications

References 34 publications

Physiological Roles of Inward-Rectifying K+ Channels.

Physiological Roles of Inward-Rectifying K+ Channels.

Roles of Higher Plant K+ Channels

Predicting effects of cations on copper toxicity to lettuce (Lactuca sativa) by the biotic ligand model

Contact Info

Product

Resources

About