Magazine article Science News

Robo Receptor: Researchers Engineer a Brain Ion Channel to Take Its Cues from Light

Magazine article Science News

Robo Receptor: Researchers Engineer a Brain Ion Channel to Take Its Cues from Light

Article excerpt

Teasing apart the complex circuitry of the brain might someday proceed with the flip of a switch, now that scientists have invented a light-responsive version of a common class of cell-surface proteins. The design permits precise control over whether channels into neurons are opened or closed to the ions that propagate nerve impulses.

To send information quickly, the brain relies on the neurotransmitter glutamate. This chemical attaches to the inside of a clamshell-shaped part of the glutamate receptor, a protein on the surface of nerve cells. Once that occurs, the clamshell closes and the receptor's ion channel opens.

Researchers had previously constructed a few examples of light-controlled receptors. But Ehud Y. Isacoff, Dirk Trauner, and their colleagues at the University of California, Berkeley wanted to create a system that was applicable to the many kinds of receptors with clamshell shapes like that in the glutamate receptor.

The researchers assembled a string of compounds with glutamate at one end. In the middle of the string, they put a chemical called azobenzene, which changes its shape when illuminated by certain wavelengths of light. At the other end, the team placed maleimide, a compound that binds tightly to sulfur.

The next step was to tether the string-bound glutamate to its receptor. The group genetically engineered a version of the receptor with the sulfur-containing amino acid cysteine at a strategic spot near the lip of the clamshell. After growing lab cultures of nerve cells bearing the altered receptors, the researchers added their modified glutamate. …

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