Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2004 Nov;124(5):445–461. doi: 10.1085/jgp.200409034

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Copyright © 2004, The Rockefeller University Press

This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).

PMC Copyright notice

Figure 1. — A single human Ca_V2.1 channel shows two different modes of gating: the fast and slow modes. Cell-attached single channel recordings with 90 mM Ba²⁺ as charge carrier on HEK293 cells stably coexpressing human Ca_V2.1α₁ (α_1A-2), β_1b and α_2bδ-1 subunits. Depolarizations were 720 ms long and were delivered every 4 s from a holding potential of −80 mV. Records were sampled and filtered at 5 and 1 kHz, respectively. (A) Consecutive traces in two different periods from a patch containing a single Ca_V2.1 channel. By visual inspection, the channel was in the mode of gating shown on the left (the slow gating mode) during the first 8 min of recording, and in the mode of gating shown on the right (the fast gating mode) during the remaining 40 min. Single channel current and conductance were identical in the two periods. (B) Log–log plots of the open and closed time distributions of the same single channel in the two periods in fast and slow gating mode. The dark solid line in each plot is the best-fitting sum of two or three exponential components for the open or closed times, respectively (each exponential component is shown as a dotted line); time constants of the open times: 0.54 and 1.42 ms (relative areas 40 and 60%) for the slow mode and 0.40 and 1.36 ms (relative areas 71 and 29%) for the fast mode; time constants of the closed times: 0.34, 3.17, and 13.4 ms (relative areas 64, 14, and 22%) for the slow mode, and 0.29, 1.17, and 3.54 ms (relative areas 43, 38, and 19%) for the fast mode. (C) Open probability, p_o, as a function of voltage for the same single channel gating in the fast (empty symbol) and slow (dark symbol) mode. Fit of the two activation curves with a Boltzmann equation gives V_1/2 = 34 mV, k = 4.5 mV, and p_{o max} = 0.64 for the slow mode and V_1/2 = 29 mV, k = 6.6 mV, and p_{o max} = 0.67 for the fast mode. The companion paper (Fellin et al., 2004) describes two additional modes of gating of Ca_V2.1 channels named b and nb modes; the single channel shown here was in the nb mode for the entire duration of the recording.