Fig. 5: VSD-I conversion is linked to VDI.
From: A rich conformational palette underlies human CaV2.1-channel availability
a The four-state model used to fit VCF data. Each VSD could achieve four conformations: R1: mode-1 resting state; A1: mode-1 active state; R2, A2: mode-2 resting and active states. Transitions are defined as: R→A: activation; A→R: deactivation; mode 1 → mode 2: conversion; mode 2 → mode 1: recovery. b The steady-state occupancy of mode-1 states (p1(∞), i.e., pR1(∞) + pA1(∞)) plotted against the holding potential (Vh) in the presence of β2a. Colored area: 95% confidence interval; vertical dashed lines point to the mean V0.5; dotted lines: V0.5 95% confidence interval (parameters in Tables S2 and S3). c As in (b), now in the presence of VDI-favoring β3-subunits: all conversions are facilitated, occurring at more negative potentials (Table S2). d Mode-1 occupancy (relative to Mode 1 at Vh = −80 mV) plotted against relative current availability. The latter was calculated from inward current at 0 mV (I0, as in the red traces in Fig. 3a) relative to I0 at Vh = −80 mV. Open symbols are from individual cells, filled symbols are means. Mode-1 occupancy in VSD-I was statistically indistinguishable from current availability (p = 0.967, n = 17 cells), in contrast to VSD-III (p = 0.0389, n = 26) and VSD-IV (p = 0.0102, n = 27). Kolmogorov-Smirnov two-sided (two-sample) tests. Error bars are S.E.M.
