Choosing Channel Selectivity

Science's STKE  14 Nov 2006:
Vol. 2006, Issue 361, pp. tw387
DOI: 10.1126/stke.3612006tw387

Ion channel proteins form pores in the membranes of cells and are regulated by voltage or small messenger molecules to control information flow to and from cells. The K+ channel, important for the excitability of nerve cells, conducts only K+ ions while completely excluding a smaller ion, Na+. Valiyaveetil et al. show that this selectivity is accomplished in two ways: In the presence of K+, the pore remains open and conductive but collapses when K+ concentrations are low, excluding Na+. In addition, in the conductive state, the pore is lined with multiple binding sites that are specific for K+.

F. I. Valiyaveetil, M. Leonetti, T. W. Muir, R. MacKinnon, Ion selectivity in a semisynthetic K+ channel locked in the conductive conformation. Science 314, 1004-1007 (2006). [Abstract] [Full Text]