Dr. Roland Roth: From the Physics of Confined Fluids to a Gating Mechanism of Ion Channels
Povzetek:
From the Physics of Confined Fluids to a Gating Mechanism of Ion Channels
Dr. Roland Roth, Max Planck Institute Stuttgart, Germany
Ion channels are proteins in cell membranes with a hole in the middle that allow ion to follow their electrochemical gradient, if the gate is open. If the gate is closed no ion transport is possible.
Pores of ion channels that follow the basic architecture of the potassium channel KcsA possess a hydrophobic region which changes its conformation between a wide pore, when open, to a narrow pore, when closed. Recent studies indicate that a hydrophobic pore can "gate" by capillary evaporation, a phenomenon that is well studied in the physics of confined fluids.
With this mechanism water is expelled from the permeation pathway and to stop the ionic current although the pore remains large enough to contain several ions. We study the connection between geometrical change of a hydrophobic pore and capillary evaporation to estimate the energetics of this gating mechanism in a realistic pore geometry, e.g. the energy it takes to remove the water from the pore and the force exerted by the water on the wall of the pore.
