| Abstract: |
| Experiments measuring currents through single protein channels show unstable currents, a phenomena called the gating of a single channel. Channels switch between an `open` state with a well defined current level and `closed` states with nearly zero current. The existing mean-field theory of ion channels focuses almost solely on the open state, while the physical modeling of the dynamical features of ion channels is still in its infancy, and does not describe the transitions between open and closed states. One hypothesis is that gating corresponds to noise-induced fast transitions between multiple steady states of the underlying system. In this work, we aim to test this hypothesis. Particularly, our study focuses on the (high order) steric Poisson-Nernst-Planck-Cahn-Hilliard model since it has been successful in predicting permeability and selectivity of ionic channels in their open state, and since it gives rise to multiple steady states. We show that this system gives rise to a gating-like behavior that does not have the defining features of gating in biological systems. Furthermore, we show that noise prohibits switching in the system of study. The above phenomena strongly suggests that one has to go beyond over-damped (gradient flow) dynamics to explain the spontaneous gating of single channels. |
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