The transport of ions across biological membranes is a fundamental process which is essential to a variety of physiological phenomena. In addition to being critical to the basic metabolism and bioenergetics of most cells, it is key to many other more specific processes. Neurotransmission, muscle action and vision are just a few examples of biological events that are mediated by the transport of ions. A deeper understanding of ion transport could have far reaching consequences in several areas of biochemistry. Dr. Dewey is investigating the transmembrane ion transport kinetics for two of the better characterized transport proteins, bacteriorhodopsin and calcium ATPase. Knowledge of the rates of the individual, elementary reaction steps is required for a detailed, molecular description of an ion transport process. A modulation relaxation kinetic technique developed in his laboratory will be used. This method will provide new information for evaluating reaction mechanisms.