A calcium- and voltage-dependent cation channel in the tonoplast of Saccharomyces cerevisiae
- Yale School of Medicine, New Haven, CT (USA)
Ion channels have been studied in the tonoplast of Saccharomyces cerevisiae by means of patch-recording techniques. The main type of channel seen thus far in excised membrane patches is a cation channel having an open-channel conductance of {approx}120 pS (in 100 mM KCl) and relative permeabilities of 1:1:0.1, for K{sup +}:Na{sup +}:Cl{sup {minus}}. Channel open probability is strongly voltage-dependent, being highest at large negative voltages (i.e., >70 mV, cytoplasm negative to the vacuole). Current-voltage (I-V) curves obtained by averaging individual channel currents over a long time (1-2 min) show marked rectification and agree well with steady-state I-V curves from whole-vacuole records. Channel opening is also strongly regulated by cytoplasmic Ca{sup ++}: openings are rare at or below 0.1 {mu}M Ca{sup ++}, but increase sigmoidally with Ca{sup ++} concentrations above 1 {mu}M, to reach a maximal open probability of {approx}0.5 at 2-5 mM free Ca{sup ++}.
- OSTI ID:
- 5726556
- Report Number(s):
- CONF-9007196-; CODEN: PPYSA
- Journal Information:
- Plant Physiology, Supplement; (USA), Vol. 93:1; Conference: Annual meeting of the American Society of Plant Physiologists, Indianapolis, IN (USA), 29 Jul - 2 Aug 1990; ISSN 0079-2241
- Country of Publication:
- United States
- Language:
- English
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