A glutamate receptor photo-switch.

Two labs at UC Berkeley (Isacoff & Trauner) have just published a "reversibly caged glutamate" in the Journal of the American Chemical Society (DOI: 10.1021/ja067269o)! They use information gleaned from the pharmacology literature (J. Med. Chem. 2000, 43, 1958-1968) to make a glutamate derivative that changes its affinity for certain types of excitatory glutamate receptors. Using 380 nm light they depolarise neurons, but with 500 nm light they reverse this reaction.

The idea is not new, Harry Wasserman did similar things in the 1970s with "bis-Q", that was later exploited by a young Henry Lester. The problem with bis-Q was that its inactive form was an antagonist, so this prevented useful experiments.

Isacoff & Trauner have revived this cool idea in a very elegant paper. It will be intteresting to see if it goes beyond the gee-wiz to give real biology.