ION CHANNEL CLOSE-UP
CARMEN DRAHL · Chemical & Engineering News · 2007
A HYBRID ION CHANNEL has given researchers the most detailed look yet at the chemical structure and interactions underpinning the function of these membrane-embedded proteins ( Nature 2007, 450, 370 and 376). The new structure, determined by X-ray crystallography, was made possible by transplanting a key component from a related channel protein. It shows that the lipid bilayer surrounding the channel plays an important role in its structure and function. Voltage-gated potassium ion channels are central to fundamental biological processes such as muscle contraction. They balance the ebb and flow of charge in nerve cell membranes by opening their gates in response to shifts in charge distribution. The structural basis for the mechanism of voltage detection, however, remains controversial. One theory, developed by Rockefeller University biophysicist and crystallographer Roderick MacKinnon, is that a portion of the voltage sensor, known as the paddle, moves at the cell’s protein-lipid interface to mediate gating. The new structure provides chemical ...