Structure, function and drug interactions in voltage-gated sodium channels. (360G-Wellcome-078080_Z_05_Z)

Sodium channels are responsible for mediating ion permeability in nerve and cardiac cells; different isoforms are responsible for either producing a voltage potential essential to neurotransmission or creating the initial upstroke of the action potential seen in electrocardiograms. A number of neurological and cardiovascular diseases involving sodium channel mutations have been identified, and these channels are good potential targets for rational drug design. In preliminary work we have isolated, purified, and structurally- and functionally- characterised sodium channels from electric eels, which have a high sequence identity with the human sodium channels, and which can be prepared in sufficient quantities for 2D crystallisations. Furthermore we have developed a circular dichroism spectroscopic assay that enables us to distinguish between the various functional states, inactivated, open, closed, etc., of the channels. This project will use 2D crystallography and electron microscopy to provide 3D structural information on this pharmacologically-important membrane protein. The use of drugs and toxins to stabilise, or 'trap', channel molecules in conformations associated with specific functional states (as monitored by Cd spectroscopy) should provide information that improves the homogeneity of the population, thereby improving the crystal order, and should aid in the understanding of the structural basis of these different states.