Nonsensing residues in S3-S4 linker's C terminus affect the voltage sensor set point in K+ channels.

ABSTRACT: Voltage sensitivity in ion channels is a function of highly conserved arginine residues in their voltage-sensing domains (VSDs), but this conservation does not explain the diversity in voltage dependence among different K+ channels. Here we study the non-voltage-sensing residues 353 to 361 in Shaker K+ channels and find that residues 358 and 361 strongly modulate the voltage dependence of the channel. We mutate these two residues into all possible remaining amino acids (AAs) and obtain Q-V and G-V curves. We introduced the nonconducting W434F mutation to record sensing currents in all mutants except L361R, which requires K+ depletion because it is affected by W434F. By fitting Q-Vs with a sequential three-state model for two voltage dependence-related parameters (V0, the voltage-dependent

SUBMITTER: Carvalho-de-Souza JL 

PROVIDER: S-EPMC5806678 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature