Description of modal gating of the cardiac calcium release channel in planar lipid membranes.
AUTOR(ES)
Zahradníková, A
RESUMO
Single channel activity of the cardiac ryanodine-sensitive calcium-release channel in planar lipid membranes was studied in order to elucidate the calcium-dependent mechanism of its steady-state behavior. The single channel kinetics, observed with Cs+ as the charge carrier at different activating (cis) Ca2+ concentrations in the absence of ATP and Mg2+, were similar to earlier reports and were extended by analysis of channel modal behavior. The channel displayed three episodic levels of open probability defining three gating modes: H (high activity), L (low activity), and I (no activity). The large difference in open probabilities between the two active modes resulted from different bursting patterns and different proportions of two distinct channel open states. I-mode was without openings and can be regarded as the inactivated mode of the channel; L-mode was composed of short and sparse openings; and H-mode openings were longer and grouped into bursts. Modal gating may explain calcium-release channel adaptation (as transient prevalence of H-mode after Ca2+ binding) and the inhibitory effects of drugs (as stabilization of mode I), and it provides a basis for understanding the regulation of calcium release.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1236411Documentos Relacionados
- A minimal gating model for the cardiac calcium release channel.
- Channel-forming properties of cecropins and related model compounds incorporated into planar lipid membranes.
- Characterization of the ion channels formed by poliovirus in planar lipid membranes.
- Different channel properties of Torpedo acetylcholine receptor monomers and dimers reconstituted in planar membranes.
- Effect of ryanodine on cardiac calcium current and calcium channel gating current.