Development and Optimization of Calcium Fluorescent Sensors Based on BK Ion Channels

Abstract

H þ currents when expressed in HEK-293 cells. The data indicate that H þ transfer is unlikely to be mediated by H þ shuttling through pairs of nearly acidic side chains, but are consistent with the hypothesis that 'aqueous' or water-wire proton transfer is the primary mechanism of H þ conduction in Hv1. Different mutant combinations produce similar defects in pH-dependent gating, suggesting that interactions among networked side chains confer emergent biophysical properties in Hv1. Experimental data were used to build a refined activatedstate Hv1 VS model structure (Hv1 J) that was subjected to molecular dynamics simulation. Although Hv1 J is similar overall to Hv1 B (Ramsey, et al., 2010), differences in the positions of specific side chains suggest a channel-opening conformational rearrangement that follows S4 movement, as predicted from gating currents (De La Rosa, et al., 2016).