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Unitary anion currents through phospholemman channel molecules
J R Moorman1, S J Ackerman, G C Kowdley
1Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville 22908, USA.
Nature
|October 26, 1995
Summary
Phospholemman (PLM) forms ion channels, making it the smallest known membrane protein to do so. This discovery suggests PLM
Area of Science:
- Membrane biophysics
- Ion transport mechanisms
- Molecular biology
Background:
- Phospholemman (PLM) is a small membrane protein known to induce currents.
- Its precise function as an ion channel or regulator remained unclear.
Purpose of the Study:
- To determine if Phospholemman (PLM) functions as an ion channel.
- To characterize the ion transport properties of PLM.
Main Methods:
- Measuring unitary anion currents in planar lipid bilayers with purified recombinant PLM.
- Analyzing currents in excised patches from oocytes expressing PLM.
- Quantifying radiolabeled taurine flux in oocytes.
Main Results:
- Recombinant PLM formed ion channels in planar lipid bilayers.
- Oocyte patches expressing PLM showed similar channel activity.
- Taurine was highly permeant through PLM channels.
- PLM expression enhanced taurine transport in oocytes.
Conclusions:
- Phospholemman (PLM) is a functional ion channel, the smallest identified to date.
- PLM's taurine selectivity points to a role in cell volume regulation.