Construction and validation of a homology model of the human voltage-gated proton channel hH V 1

What is it about?

We evaluate two open-state models of hHV1, using extensive molecular dynamics simulations and experiment. Both approaches lead to a model with an open-state salt bridge between Asp112 and Arg208. The first Arg partakes in an external charge cluster; the third in an internal cluster. If proton channels were content to mimic other voltage-gated channels, they might move all three S4 Arg residues from internal to external vestibules. But instead they opt for a stable open state!

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Why is it important?

This model implies that the S4 segment moves a much shorter distance during channel opening than was previously believed. This idea was strongly supported by a recent EPR study by Li et al (PNAS, 2015).