Inward and outward potassium currents through the same chimeric human Kv channel.

Voltage-gated ion channels are among the most intensely studied membrane proteins today and a variety of techniques has led to a basic mapping of functional roles onto specific regions of their structure. The architecture of the proteins appears to be modular and segments associated with voltage sensing and the pore lining have been identified. However, the means by which movement of the sensor is transduced into channel opening is still unclear. In this communication, we report on a chimeric potassium channel construct which can function in two distinct operating voltage ranges, spanning both inward and outward currents with a non-conducting intervening regime. The observed changes in operating range could be brought about by perturbing either the direction of sensor movement or the process of transducing movements of the sensor into channel opening and closing. The construct could thus provide a means to identify the machinery underlying these processes.