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. Author manuscript; available in PMC: 2011 Sep 1.
Published in final edited form as: Trends Biotechnol. 2010 Jul 29;28(9):468–475. doi: 10.1016/j.tibtech.2010.06.001

Figure 3.

Figure 3

Reversible photochemical activation of a potassium ion (K+) channel. (a) Schematic of PAL-gated K+ channel. The sphere labeled with a plus sign represents a quaternary ammonium group, which blocks the channel when the diazobenzene is in the trans conformation. Irradiation at 380 nm switches the diazobenzene from trans to cis, thus enabling K+ flow. Irradiation with 500 nm light reverses the switching event, thus blocking the ion channel. (b) Light-controlled membrane potential of a PAL-gated K+ channel measured in dependence of light irradiation.