Mutation of voltage-sensor domains (VSDs) can sometimes lead to ions leaking across the membrane through the VSDs themselves. Ion conduction through the mutated VSD of the Shaker Kv channel was coined the “omega current” in 2005 by Tombola, Pathak and Isacoff (Tombola et al., 2005). Many different mutations have been identified that result in current leaking through VSDs in many different channels. This current can be carried by a variety of ions including H+, Li+, K+, Cs+ and guanidinium. It has also been shown that naturally occurring mutations in VSDs that result in omega current leak can lead to channelopathies (diseases caused by malfunctioning ion channels, learn more about them out on wikipedia). In this post I will discuss a mutation of the Shaker Kv channel that results in omega current leak. I will address how this current arises and briefly what it can tell us about the mechanism of voltage-sensing.
