Presentation description

Voltage-gated ion channels transport charged ions across a membrane in response to changes in voltage. Ions flow through the channel's selectivity filter, a region within the pore that uses electrostatic interactions to attract or repel ions. KcsA, MthK, and Shaker are voltage-gated potassium channels that, despite having identical selectivity filters, facilitate potassium ions at different rates. This project aims to investigate whether the selectivity filters contribute to the observed differences by using computational methods to quantify voltage responses. To bypass computational limitations of creating membrane potentials, we apply a linear electric field to the system, inducing ion displacement. The voltage response is then examined by calculating dimensionless coupling factors, which quantify the relationship between the position of ions and their sensitivity to the applied electric field. By analyzing these factors under varying concentrations and voltages, we aim to determine whether or not the difference in flux rate is influenced by the selectivity filter. Future research directions include exploring how mechanistic pathways, defined by varying ion occupancies within the channel pore, might contribute to flux rates. The computational modeling methods used also serve as a continued area for refinement. In particular, minimizing physical restraints and using energy-dependent approximations could improve the reproducibility of experimental results. Strong agreement with experimental data would not only strengthen the validity of the modeling methods but also better support future computational predictions.