Chambers James J, Banghart Matthew R, Trauner Dirk, Kramer Richard H
Department of Molecular and Cell Biology, University of California, Berkley, CA 94720, USA.
J Neurophysiol. 2006 Nov;96(5):2792-6. doi: 10.1152/jn.00318.2006. Epub 2006 Jul 26.
To trigger action potentials in neurons, most investigators use electrical or chemical stimulation. Here we describe an optical stimulation method based on semi-synthetic light-activated ion channels. These SPARK (synthetic photoisomerizable azobenzene-regulated K(+)) channels consist of a synthetic azobenzene-containing photoswitch and a genetically modified Shaker K(+) channel protein. SPARK channels with a wild-type selectivity filter elicit hyperpolarization and suppress action potential firing when activated by 390 nm light. A mutation in the pore converts the K(+)-selective Shaker channel into a nonselective cation channel. Activation of this modified channel with the same wavelength of light elicits depolarization of the membrane potential. Expression of these depolarizing SPARK channels in neurons allows light to rapidly and reversibly trigger action potential firing. Hence, hyper- and depolarizing SPARK channels provide a means for eliciting opposite effects on neurons in response to the same light stimulus.
为了触发神经元的动作电位，大多数研究人员使用电刺激或化学刺激。在此，我们描述一种基于半合成光激活离子通道的光刺激方法。这些SPARK（合成的光异构化偶氮苯调节的K(+)）通道由一种含合成偶氮苯的光开关和一种基因改造的Shaker K(+)通道蛋白组成。具有野生型选择性过滤器的SPARK通道在被390 nm光激活时会引发超极化并抑制动作电位发放。孔道中的一个突变将K(+)选择性的Shaker通道转变为非选择性阳离子通道。用相同波长的光激活这种修饰后的通道会引发膜电位的去极化。这些去极化的SPARK通道在神经元中的表达使光能够快速且可逆地触发动作电位发放。因此，超极化和去极化的SPARK通道提供了一种手段，可针对相同的光刺激对神经元产生相反的效应。
