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Ion Channel Silences Neurons: Trauner

From C&E News Concentrates: November 29, 2004
Volume 82, Number 48
p. 24

A clever new chemical trick that renders specific neurons sensitive to light may help neuroscientists tease apart how individual neurons are linked into complex neural networks [Nat. Neurosci., published online Nov. 21, http://dx.doi.org/10.1038/nn1356]. Richard H. Kramer, Dirk Trauner, and coworkers at the University of California, Berkeley, introduced a reactive cysteine handle near the pore of a common K+ channel. The researchers then expressed this modified channel in rat neurons and tagged its reactive cysteine with a photoisomerizable azobenzene tether tipped with a quaternary ammonium ion, a moiety known to plug K+ channels' ion-conducting pore. Long-wavelength light causes the azobenzene to adopt an extended trans configuration that allows the ammonium ion to plug the pore (left). But short-wavelength light generates the shorter cis configuration and lets K+ rush out of the neuron (right), rendering the cell inactive. These photosensitive channels allow rapid, precise, and reversible control over specific neurons, making them valuable tools for dissecting complex neural networks in cell culture, Trauner says.

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