Regensburg 2019 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
BP: Fachverband Biologische Physik
BP 6: Poster I
BP 6.71: Poster
Montag, 1. April 2019, 17:30–19:30, Poster B2
Mechanisms of Permeation in Potassium Channels — •Maximilian Vossel1,2 and Bert de Groot2 — 1Mathematical Biophysics Group, Max-Planck-Institute for Biophysical Chemistry (Göttingen) — 2Computational Biomolecular Dynamics Group, Max-Planck-Institute for Biophysical Chemistry (Göttingen)
K+ channels are proteins that facilitate the passive permeation of K+ ions through the cell membrane. They conduct at rates close to the diffusion limit while selecting against Na+ ions by more than a thousandfold. It has been confirmed that the channels’ narrowest constriction – the selectivity filter – forces the K+ ions to move in single file and is thereby responsible for both high current and high fidelity in rejecting Na+.
In this work, we aim for a deeper understanding of the permeation mechanism by comparing computational models of different members of the K+ channel family against each other. Using data from (recently published) non–equilibrium steady state molecular dynamics simulations of permeating K+ channels we built discrete models of the permeation mechanism on a reduced phase space.
We could show that the ‘direct knock-on’ mechanism, where K+ ions are in immediate adjacency to each other, is a robust process of permeation. Although exhibiting small, measurable variations, it is conserved in its main theme through all studied channels and force fields. Exploiting local detailed balance we estimated a lower bound for the voltage drop across the selectivity filter, finding values which are in very good agreement with those expected from the literature.