Joseph E. Reiner, Arvind Balijepalli, Joseph W. F. Robertson, Jason Campbell, John Suehle, and John J. Kasianowicz
As nanometer-scale portals in biological membranes, protein ionic channels act as gatekeepers, controlling the traffic of ions and macromolecules into and out of cells, organelles, and the nucleus. Because of their ubiquitous nature, proper channel function is critical to all aspects of life. One might suppose that the most obvious feature of these transmembrane proteins, a nanometer-scale hole in a ca. 4 nm thick phospholipid bilayer membrane, renders channels as the simplest of biological machines. However, channels have evolved in rather sophisticated ways to control a wide range of biological function. We briefly discuss below some of the roles channels play in biology, as well as why they and mimics of them are emerging as effective biosensors for characterizing and quantifying many types of molecules. We then describe some examples of how such a novel measurement capability could prove useful for detecting disease states, assessing the efficacy of therapeutic agents, and managing the treatment of human disease.