About Channelrhodopsin Wiki
This is a wiki on channelrhodopsins, for an AP biology project. For this reason, editing is limited to project members.
Channelrhodopsins are a class of optic proteins that have many emerging and promising uses in bioengineering.
In what organism is the protein found? How does it help the organism?
Channelrhodopsins are a class of proteins that respond quickly to, and have high sensitivity to, light intensities. They are found mainly in blue-green algae (Chlamydomonas reinhardtii) and they respond to light intensities by generating signals that assist the organism in finding a location with better conditions for photosynthesis. These molecules help individual alga compete with other alga for the best conditions to perform photosynthesis, by determining where the most productive areas are.
How was channelrhodopsin discovered?
Channelrodopsin was first documented and analyzed in 2002, when Georg Nagel and his colleagues first isolated and described Channelrhodopsin-1 (ChR1). Channelrhodopsin-2 was later isolated from Chlamydomonas reinhardtii as well, in 2005 by the Deisseroth neurobiology group. It had been noticed, long before, that blue-green algae could sense and move towards light despite the lack of eyes, but only recently have independent groups had a breakthrough in identifying the genes that allowed algae to sense light without eyes. Going through the algae genome, scientists noticed that although retinal pigments and the new molecules were both genetically similar and photosensitive, they transmitted signals differently. The new molecules instead acted as light-gated ion channels, generating electrical signals. Upon testing the channels in a lab dish, it was discovered that some proteins, like channelrhodopsin, "activate" cells by sending out signals, while others "inhibit" cells by signaling them to shut down. Researchers were then able to conclude that light directly opened these channels, allowing ions to flow through and control neuron electrical activity. In addition, it does not distinguish between cations, letting all positive ions (K+, Ca2+, etc) to pass into the cell.