Ca^sub v^1.4 Encodes a Calcium Channel with Low Open Probability and Unitary Conductance

When transiently expressed in tsA-201 cells, Ca^sub v^1.4 calcium channels support only modest whole-cell currents with unusually slow voltage-dependent inactivation kinetics. To examine the basis for this unique behavior we used cell-attached patch single-channel recordings using 100 mM external ba...

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Bibliographic Details
Published in:Biophysical journal 2005-11, Vol.89 (5), p.3042
Main Authors: Doering, Clinton J, Jawed Hamid, Simms, Brett, McRory, John E, Zamponi, Gerald W
Format: Article
Language:English
Subjects:
Biophysics
Cellular biology
Enzymes
Kinetics
Online Access:Get full text
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Summary:When transiently expressed in tsA-201 cells, Ca^sub v^1.4 calcium channels support only modest whole-cell currents with unusually slow voltage-dependent inactivation kinetics. To examine the basis for this unique behavior we used cell-attached patch single-channel recordings using 100 mM external barium as the charge carrier to determine the single-channel properties of Ca^sub v^1.4 and to compare them to those of the Ca^sub v^1.2. Ca^sub v^1.4 channel openings occurred infrequently and were of brief duration. Moreover, openings occurred throughout the duration of the test depolarization, indicating that the slow inactivation kinetics observed at the whole-cell level are caused by sustained channel activity. Ca^sub v^1.4 and Ca^sub v^1.2 channels displayed similar latencies to first opening. Because of the rare occurrence of events, the probability of opening could not be precisely determined but was estimated to be
ISSN:0006-3495
1542-0086