NSC1: a novel high-current inward rectifier for cations in the plasma membrane of Saccharomyces cerevisiae

• Published in: FEBS letters Vol. 432; no. 1; pp. 59 - 64
• Main Authors: Bihler, Hermann, Slayman, Clifford L, Bertl, Adam
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 31-07-1998
• Subjects: Calcium - metabolism; Calcium inhibition; Cation yeast; Cations - metabolism; Cell Membrane Permeability; Electric Conductivity; Inward rectifier; Ion Channels - metabolism; Membrane potential; Non-specific channel; Patch-Clamp Techniques; Potassium - metabolism; Saccharomyces cerevisiae - physiology; Saccharomyces cerevisiae Proteins; Salt tolerance; Salt tolerance; Non-specific channel; Cation yeast; Membrane potential; Inward rectifier; Calcium inhibition
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/S0014-5793(98)00832-1

The plasma membrane of the yeast
Saccharomyces cerevisiae possesses a non-specific cation `channel', tentatively dubbed NSC1, which is blocked by normal (mM) calcium and other divalent metal ions, is unblocked by reduction of extracellular free divalents below ∼10 μM, and is independent of the identified potassium channel and porters in yeast, Duk1p, Trk1p, and Trk2p. Ion currents through NSC1, observed by means of whole-cell patch recording, have the following characteristics:
Large amplitude, often exceeding 1 nA of K
+/cell at −200 mV, in tetraploid yeast, sufficient to double the normal intracellular K
+ concentration within 10 s;
non-saturation at large negative voltages;
complicated activation kinetics, in which ∼50% of the total current arises nearly instantaneously with a voltage-clamp step, while the remainder develops as two components, with time constants of ∼100 ms and ∼1.3 s; and
voltage independence of both the activation time constants and the associated fractional current amplitudes.