Journal of Biological Chemistry vol:268 issue:32 pages:23777-9
Ion channels are generally classified as voltage- or ligand-gated channels based upon their ability to respond to a change in the transmembrane voltage or to a specific ligand interaction. The voltage sensor of voltage-gated ion channels is thought to be contained within the fourth putative transmembrane segment, S4, and is characterized by basic residues typically spaced apart. Thus far, a full understanding of all charges contributing to the voltage sensor of voltage-gated potassium channels has been lacking since several neutralization mutants in S4 could not be functionally expressed. By construction of multimeric cDNAs encoding a mammalian RCK1 (Kv1.1) potassium channel, we now report functional expression of all charge neutralizations in the S4 segment, providing a more comprehensive insight into the functioning of the voltage sensor.