Ion Channels Formed by NB,an Influenza B Virus Protein |
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Authors: | NA Sunstrom LS Premkumar A Premkumar G Ewart GB Cox PW Gage |
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Institution: | (1) John Curtin School of Medical Research, Australian National University, Canberra ACT 2601 Australia, AU |
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Abstract: | The influenza B virus protein, NB, was expressed in Escherichia coli, either with a C-terminal polyhistidine tag or with NB fused to the C-terminus of glutathione S-transferase (GST), and purified
by affinity chromatography. NB produced ion channel activity when added to artificial lipid bilayers separating NaCl solutions
with unequal concentrations (150–500 mm
cis, 50 mm
trans). An antibody to a peptide mimicking the 25 residues at the C-terminal end of NB, and amantadine at high concentration (2–3
mm), both depressed ion channel activity. Ion channels had a variable conductance, the lowest conductance observed being approximately
10 picosiemens. At a pH of 5.5 to 6.5, currents reversed at positive potentials indicating that the channel was more permeable
to sodium than to chloride ions (PNa/PCl∼ 9). In asymmetrical NaCl solutions at a pH of 2.5, currents reversed closer to the chloride than to the sodium equilibrium
potential indicating that the channel had become more permeable to chloride than to sodium ions (PCl/PNa∼ 4). It was concluded that, at normal pHs, NB forms cation-selective channels.
Received: 6 March 1995/Revised: 17 November 1995 |
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Keywords: | : Virus protein — Ion channels — Planar lipid bilayer |
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