Sandbox WWC3: Difference between revisions

=== Gating ===

The S1 through S4 segments make up the gating mechanism <ref name= "crystal"/>. In particular,the S4 segments consist of repeated motifs of a positively charged residue (usually Arg) followed by two hydrophobic residues <ref name= "crystal"/>. This alpha helix is exposed to the membrane electric field, and in response to a depolarization, it is displaced outwards <ref name= "crystal"/>. This causes the channel to open. S4 segments can be seen in red <scene name='69/696300/S4/1'>here</scene>. Surprisingly, each S4 chain does not contribute equally to the gating of this channel. A mutation in one chain may have a much larger effect than a mutation in another S4 chain <ref name = "struct"/>. However, these S4 segments are merely sensors. The actual gating mechanism is still up for debate, with the leading contender being the S6 segment. This mechanism would be similar to the gating of the K+ channel <ref name = "struct"/>. The outward movement of the S4 segment moves the S4-S5 linker, which pulls the S5-S^ segments and opens the pore <ref name= "crystal"/>. Overall, the voltage sensing domain makes a rolling motion of the S4-S5 linker around the pore <ref name= "crystal"/>.