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Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes
Calmodulin is a ubiquitous Ca(2+) binding protein that modulates the in vitro activity of the skeletal muscle ryanodine receptor (RyR1). Residues 3614–3643 of RyR1 comprise the CaM binding domain and mutations within this region result in a loss of both high-affinity Ca(2+)-bound calmodulin (CaCaM)...
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Formato: | Texto |
Lenguaje: | English |
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The Rockefeller University Press
2002
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Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229515/ https://www.ncbi.nlm.nih.gov/pubmed/12198090 http://dx.doi.org/10.1085/jgp.20028617 |
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author | O'Connell, Kristen M.S. Yamaguchi, Naohiro Meissner, Gerhard Dirksen, Robert T. |
author_facet | O'Connell, Kristen M.S. Yamaguchi, Naohiro Meissner, Gerhard Dirksen, Robert T. |
author_sort | O'Connell, Kristen M.S. |
collection | PubMed |
description | Calmodulin is a ubiquitous Ca(2+) binding protein that modulates the in vitro activity of the skeletal muscle ryanodine receptor (RyR1). Residues 3614–3643 of RyR1 comprise the CaM binding domain and mutations within this region result in a loss of both high-affinity Ca(2+)-bound calmodulin (CaCaM) and Ca(2+)-free CaM (apoCaM) binding (L3624D) or only CaCaM binding (W3620A). To investigate the functional role of CaM binding to this region of RyR1 in intact skeletal muscle, we compared the ability of RyR1, L3624D, and W3620A to restore excitation–contraction (EC) coupling after expression in RyR1-deficient (dyspedic) myotubes. W3620A-expressing cells responded normally to 10 mM caffeine and 500 μM 4-chloro-m-cresol (4-cmc). Interestingly, L3624D-expressing cells displayed a bimodal response to caffeine, with a large proportion of cells (∼44%) showing a greatly attenuated response to caffeine. However, high and low caffeine-responsive L3624D-expressing myotubes exhibited Ca(2+) transients of similar magnitude after activation by 4-cmc (500 μM) and electrical stimulation. Expression of either L3624D or W3620A in dyspedic myotubes restored both L-type Ca(2+) currents (retrograde coupling) and voltage-gated SR Ca(2+) release (orthograde coupling) to a similar degree as that observed for wild-type RyR1, although L-current density was somewhat larger and activated at more hyperpolarized potentials in W3620A-expressing myotubes. The results indicate that CaM binding to the 3614–3643 region of RyR1 is not essential for voltage sensor activation of RyR1. |
format | Text |
id | pubmed-2229515 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2002 |
publisher | The Rockefeller University Press |
record_format | MEDLINE/PubMed |
spelling | pubmed-22295152008-04-16 Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes O'Connell, Kristen M.S. Yamaguchi, Naohiro Meissner, Gerhard Dirksen, Robert T. J Gen Physiol Article Calmodulin is a ubiquitous Ca(2+) binding protein that modulates the in vitro activity of the skeletal muscle ryanodine receptor (RyR1). Residues 3614–3643 of RyR1 comprise the CaM binding domain and mutations within this region result in a loss of both high-affinity Ca(2+)-bound calmodulin (CaCaM) and Ca(2+)-free CaM (apoCaM) binding (L3624D) or only CaCaM binding (W3620A). To investigate the functional role of CaM binding to this region of RyR1 in intact skeletal muscle, we compared the ability of RyR1, L3624D, and W3620A to restore excitation–contraction (EC) coupling after expression in RyR1-deficient (dyspedic) myotubes. W3620A-expressing cells responded normally to 10 mM caffeine and 500 μM 4-chloro-m-cresol (4-cmc). Interestingly, L3624D-expressing cells displayed a bimodal response to caffeine, with a large proportion of cells (∼44%) showing a greatly attenuated response to caffeine. However, high and low caffeine-responsive L3624D-expressing myotubes exhibited Ca(2+) transients of similar magnitude after activation by 4-cmc (500 μM) and electrical stimulation. Expression of either L3624D or W3620A in dyspedic myotubes restored both L-type Ca(2+) currents (retrograde coupling) and voltage-gated SR Ca(2+) release (orthograde coupling) to a similar degree as that observed for wild-type RyR1, although L-current density was somewhat larger and activated at more hyperpolarized potentials in W3620A-expressing myotubes. The results indicate that CaM binding to the 3614–3643 region of RyR1 is not essential for voltage sensor activation of RyR1. The Rockefeller University Press 2002-09 /pmc/articles/PMC2229515/ /pubmed/12198090 http://dx.doi.org/10.1085/jgp.20028617 Text en Copyright © 2002, 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/). |
spellingShingle | Article O'Connell, Kristen M.S. Yamaguchi, Naohiro Meissner, Gerhard Dirksen, Robert T. Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes |
title | Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes |
title_full | Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes |
title_fullStr | Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes |
title_full_unstemmed | Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes |
title_short | Calmodulin Binding to the 3614–3643 Region of RyR1 Is Not Essential for Excitation–Contraction Coupling in Skeletal Myotubes |
title_sort | calmodulin binding to the 3614–3643 region of ryr1 is not essential for excitation–contraction coupling in skeletal myotubes |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2229515/ https://www.ncbi.nlm.nih.gov/pubmed/12198090 http://dx.doi.org/10.1085/jgp.20028617 |
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