کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2185769 | 1096008 | 2010 | 13 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: The Branched Photocycle of the Slow-Cycling Channelrhodopsin-2 Mutant C128T The Branched Photocycle of the Slow-Cycling Channelrhodopsin-2 Mutant C128T](/preview/png/2185769.png)
Channelrhodopsins (ChRs) of green algae such as Chlamydomonas are used as neuroscience tools to specifically depolarize cells with light. A crude model of the ChR2 photocycle has been recently established, but details of the photoreactions are widely unknown. Here, we present the photoreactions of a slow-cycling ChR2 mutant (step function rhodopsin), with C128 replaced by threonine and 200-fold extended lifetime of the conducting-state P520. At a late state of the photocycle, a fraction of the proteins branches off into an inactive species, P380, which accumulates during prolonged illumination. At neutral pH, P380 is converted into P353, a species with a characteristic fine-structured spectrum that is interpreted as retroretinyl chromophore. The described branching reactions should be considered, when ChR is used as a neuroscience tool, especially in the case of fluorescence imaging at high light intensities.
Journal: Journal of Molecular Biology - Volume 398, Issue 5, 21 May 2010, Pages 690–702