Voltage-gated cation channels (VGCCs) are membrane proteins critical for electric signaling in  cells. The superfamily of VGCCs includes four major classes: Na+, Ca2+, K+ and non-selective cationic channels, corresponding to Nav, Cav, Kv, and HCN channels, respectively. Owing to their structural similarity, their voltage-sensing and gating processes are expected to be similar to that unveiled for Kv channels. However, the intrinsic conduction properties of the selectivity filter must be specific among members of the family. Very recently, the x-ray structure of the prokaryotic-Nav channel, NavAb, was determined in a �pre-open� state, opening new possibilities in deciphering conduction in Na+ channels. Here, by modeling the open-pore conformation, we have applied voltage-clamped molecular dynamics simulations to engender several events of Na+ conduction through the channel. Our results suggest that NavAb employs the �knock-on� mechanism of K+ channels to transport ions, involving however a distinct �off-register� binding mode of ions to the filter.

Watching ions and water conduction through sodium channels

244th National Meeting (2012)

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