Bertl, A. and Slayman, C. L. (1992):
Complex modulation of cation channels in the tonoplast and plasma membrane of Saccharomyces cerevisiae: single-channel studies.
172, In: The Journal of experimental biology, pp. 271-287, ISSN 0022-0949, [Online-Edition: http://jeb.biologists.org/cgi/reprint/172/1/271],
[Article]
Abstract
Detailed patch-clamp studies have been made of ion channels in the plasma membrane and tonoplast of the yeast Saccharomyces cerevisiae. The predominant tonoplast channel is a high-conductance cation-selective inward rectifier (passing ions easily into the cytoplasm from the vacuole), with its open probability (Po) peaking at about -80 mV (cytoplasm negative) and falling to near zero at +80 mV. It has a maximal slope conductance of approximately 150 pS in 100 mmol l-1 KCl, and conducts Na+, K+ and Ca2+. Elevated cytoplasmic Ca2+ concentration, alkaline pH and reducing agents can activate the channel, its likely physiological function being to adjust cytoplasmic Ca2+ concentration from the vacuolar reservoir. The predominant plasma-membrane channel is a strongly outward rectifying K+ channel (passing K+ easily out of the cytoplasm to the extracellular medium), which is activated by positive-going membrane voltages as well as by elevated cytoplasmic Ca2+ concentration and alkaline pH. Interaction between membrane voltage and [Ca2+]cyt is complex and defines three parallel closed states for the channel: a Ca(2+)-independent brief closure (I), a calcium-inhibited long closure (G) and, at large positive voltages, a calcium-induced brief blockade (B). This channel is likely to function in steady-state turgor regulation and in charge balancing during proton-coupled substrate uptake.
| Item Type: | Article |
|---|---|
| Erschienen: | 1992 |
| Creators: | Bertl, A. and Slayman, C. L. |
| Title: | Complex modulation of cation channels in the tonoplast and plasma membrane of Saccharomyces cerevisiae: single-channel studies. |
| Language: | English |
| Abstract: | Detailed patch-clamp studies have been made of ion channels in the plasma membrane and tonoplast of the yeast Saccharomyces cerevisiae. The predominant tonoplast channel is a high-conductance cation-selective inward rectifier (passing ions easily into the cytoplasm from the vacuole), with its open probability (Po) peaking at about -80 mV (cytoplasm negative) and falling to near zero at +80 mV. It has a maximal slope conductance of approximately 150 pS in 100 mmol l-1 KCl, and conducts Na+, K+ and Ca2+. Elevated cytoplasmic Ca2+ concentration, alkaline pH and reducing agents can activate the channel, its likely physiological function being to adjust cytoplasmic Ca2+ concentration from the vacuolar reservoir. The predominant plasma-membrane channel is a strongly outward rectifying K+ channel (passing K+ easily out of the cytoplasm to the extracellular medium), which is activated by positive-going membrane voltages as well as by elevated cytoplasmic Ca2+ concentration and alkaline pH. Interaction between membrane voltage and [Ca2+]cyt is complex and defines three parallel closed states for the channel: a Ca(2+)-independent brief closure (I), a calcium-inhibited long closure (G) and, at large positive voltages, a calcium-induced brief blockade (B). This channel is likely to function in steady-state turgor regulation and in charge balancing during proton-coupled substrate uptake. |
| Journal or Publication Title: | The Journal of experimental biology |
| Volume: | 172 |
| Divisions: | 10 Department of Biology ?? fb10_botanik ?? 10 Department of Biology > Yeast Membrane Biology |
| Date Deposited: | 25 Nov 2010 15:27 |
| Official URL: | http://jeb.biologists.org/cgi/reprint/172/1/271 |
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