A cell-free system for assaying ion channel function

DESCRIPTION (provided by applicant): Ion channels function as signaling intermediaries that are involved in nerve signal propagation, muscle contraction, cardiopulmonary regulation, and cell metabolism. Their importance is underscored by the existence of dozens of ion channel-specific drugs that treat important neurological and cardiovascular diseases. Despite their importance in human health, ion channels remain complex and difficult proteins to study. Ion channels are topologically complex membrane proteins that span the lipid bilayer of the cell several times, often form oligomers, and contain complex regulatory elements within their tertiary structure. Living cells are typically necessary for ion channel assays because the cellular lipid membrane maintains both ion channel structure and the differences in ion concentration that are the basis of cellular electrical signals. However, cells have inherent limitations for nano- and micro-scale applications. A better way to study ion channels is needed within microfluidic drug screening devices, for detecting ion and voltage changes in subcellular compartments too small to be measured directly, and for emerging nanotechnology applications. The purpose of this proposal is to enable the measurement of ion channel function on the nano-scale for application within microfluidic devices and at subcellular locations. We have developed a novel technology, the lipoparticle that makes it possible to present ion channels and other membrane proteins in native conformation in a stable, nano-scale format. In research that has spanned the past five years, we have defined the basic characteristics of lipoparticles as drug discovery tools. We have incorporated ion channels into lipoparticles, but have had no way of measuring their ability to function. We propose here to develop a nano-scale sensor for detecting ion channel function.