S4-based voltage sensors have three major conformations.

Voltage sensors containing the charged S4 membrane segment display a gating charge vs. voltage (Q-V) curve that depends on the initial voltage. The voltage-dependent phosphatase (Ci-VSP), which does not have a conducting pore, shows the same phenomenon and the Q-V recorded with a depolarized initial voltage is more stable by at least 3RT.

Silicon chip-based patch-clamp electrodes integrated with PDMS microfluidics.

We report on a silicon wafer-based device that can be used for recording macroscopic ion channel protein activities across a diverse group of cell-types. Gigaohm seals were achieved for CHO-K1 and RIN m5F cells, and both cell-attached and whole-cell mode configurations were also demonstrated. Two distinct intrinsic potassium ion channels were recorded in whole-cell mode for HIT-T15 and RAW 264.

Detecting rearrangements of shaker and NaChBac in real-time with fluorescence spectroscopy in patch-clamped mammalian cells.

Time-resolved fluorescence detection of site-directed probes is a major tool in the investigation of structure-function relationships of voltage-dependent ion channels. However, the technique has been limited so far to the Xenopus-oocyte system making it difficult to study proteins, like, e.g.

A proton pore in a potassium channel voltage sensor reveals a focused electric field.

Voltage-dependent potassium channels are essential for the generation of nerve impulses. Voltage sensitivity is conferred by charged residues located mainly in the fourth transmembrane segment (S4) of each of the four identical subunits that make up the channel. These charged segments relocate when the potential difference across the membrane changes, controlling the ability of the pore to conduct ions.