The Gating Kinetics of the Slow Vacuolar Channel. A Novel Mechanism for SV Channel Functioning?

The Gating Kinetics of the Slow Vacuolar Channel. A Novel Mechanism for SV Channel Functioning? Although there is consensus that the slow vacuolar or SV channel is a Ca2+ release channel, the underlying mechanism of operation is still controversial. The main reason is that the voltage sensitivity of SV gating seems to exclude activation at hyperpolarized (physiological) membrane potentials. Inspired by a study of Gambale et al. (1993) and supported by simulation studies presented here, we interpreted SV activation and deactivation kinetics in terms of a cyclic state diagram originally applied to animal cation-selective channels. A cyclic state diagram allows two pathways of activation operating in opposite directions. One pathway represents the frequently observed slow activation at moderate depolarization (<130 mV). With the open state (O) next to the closed state initially occupied (C 1), direct transitions from C 1 to O can account for the fast activation observed at higher depolarized potentials (>130 mV). We hypothesize that similar state transitions directly to O may also occur during hyperpolarization. The implication of this proposed mechanism is that SV accomplishes its physiological role during hyperpolarization-evoked deactivation. Despite their rare occurrence and possibly short duration, these opening events may last long enough to substantially raise the local cytosolic free Ca2+ level at the channel mouth by as much as 600 nM/ms. Because under in vivo conditions the Ca2+ flux is inwardly directed, the mechanism presented here revives the notion that the SV channel can be subject to calcium-induced calcium release. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

The Gating Kinetics of the Slow Vacuolar Channel. A Novel Mechanism for SV Channel Functioning?

Loading next page...
 
/lp/springer_journal/the-gating-kinetics-of-the-slow-vacuolar-channel-a-novel-mechanism-for-Svv2l0iGFZ
Publisher
Springer-Verlag
Copyright
Copyright © 2003 by Springer-Verlag New York Inc.
Subject
Philosophy
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-003-2022-z
Publisher site
See Article on Publisher Site

Abstract

Although there is consensus that the slow vacuolar or SV channel is a Ca2+ release channel, the underlying mechanism of operation is still controversial. The main reason is that the voltage sensitivity of SV gating seems to exclude activation at hyperpolarized (physiological) membrane potentials. Inspired by a study of Gambale et al. (1993) and supported by simulation studies presented here, we interpreted SV activation and deactivation kinetics in terms of a cyclic state diagram originally applied to animal cation-selective channels. A cyclic state diagram allows two pathways of activation operating in opposite directions. One pathway represents the frequently observed slow activation at moderate depolarization (<130 mV). With the open state (O) next to the closed state initially occupied (C 1), direct transitions from C 1 to O can account for the fast activation observed at higher depolarized potentials (>130 mV). We hypothesize that similar state transitions directly to O may also occur during hyperpolarization. The implication of this proposed mechanism is that SV accomplishes its physiological role during hyperpolarization-evoked deactivation. Despite their rare occurrence and possibly short duration, these opening events may last long enough to substantially raise the local cytosolic free Ca2+ level at the channel mouth by as much as 600 nM/ms. Because under in vivo conditions the Ca2+ flux is inwardly directed, the mechanism presented here revives the notion that the SV channel can be subject to calcium-induced calcium release.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Sep 18, 2003

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off