Fast kinetics of calcium dissociation from calsequestrin

We measured the kinetics of calcium dissociation from calsequestrin in solution or forming part of isolated junctional sarcoplasmic reticulum membranes by mixing calsequestrin equilibrated with calcium with calcium-free solutions in a stopped-flow system. In parallel, we measured the kinetics of the...

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Autores principales:	BELTRÁN,MARIANELA, BARRIENTOS,GENARO, HIDALGO,CECILIA
Lenguaje:	English
Publicado:	Sociedad de Biología de Chile 2006
Materias:	calcium-binding proteins ryanodine receptors sarcoplasmic reticulum calcium release kinetics excitation-contraction coupling skeletal and cardiac muscle
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000300011
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spelling	oai:scielo:S0716-976020060003000112014-01-24Fast kinetics of calcium dissociation from calsequestrinBELTRÁN,MARIANELABARRIENTOS,GENAROHIDALGO,CECILIA calcium-binding proteins ryanodine receptors sarcoplasmic reticulum calcium release kinetics excitation-contraction coupling skeletal and cardiac muscle We measured the kinetics of calcium dissociation from calsequestrin in solution or forming part of isolated junctional sarcoplasmic reticulum membranes by mixing calsequestrin equilibrated with calcium with calcium-free solutions in a stopped-flow system. In parallel, we measured the kinetics of the intrinsic fluorescence changes that take place following calcium dissociation from calsequestrin. We found that at 25ºC calcium dissociation was 10-fold faster for calsequestrin attached to junctional membranes (k = 109 s-1) than in solution. These results imply that calcium dissociation from calsequestrin in vivo is not rate limiting during excitation-contraction coupling. In addition, we found that the intrinsic fluorescence decrease for calsequestrin in solution or forming part of junctional membranes was significantly slower than the rates of calcium dissociation. The kinetics of intrinsic fluorescence changes had two components for calsequestrin associated to junctional membranes and only one for calsequestrin in solution; the faster component was 8-fold faster (k = 54.1 s-1) than the slower component (k = 6.9 s-1), which had the same k value as for calsequestrin in solution. These combined results suggest that the presence of calsequestrin at high concentrations in a restricted space, such as when bound to the junctional membrane, accelerates calcium dissociation and the resulting structural changes, presumably as a result of cooperative molecular interactions.info:eu-repo/semantics/openAccessSociedad de Biología de ChileBiological Research v.39 n.3 20062006-01-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000300011en10.4067/S0716-97602006000300011
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	calcium-binding proteins ryanodine receptors sarcoplasmic reticulum calcium release kinetics excitation-contraction coupling skeletal and cardiac muscle
spellingShingle	calcium-binding proteins ryanodine receptors sarcoplasmic reticulum calcium release kinetics excitation-contraction coupling skeletal and cardiac muscle BELTRÁN,MARIANELA BARRIENTOS,GENARO HIDALGO,CECILIA Fast kinetics of calcium dissociation from calsequestrin
description	We measured the kinetics of calcium dissociation from calsequestrin in solution or forming part of isolated junctional sarcoplasmic reticulum membranes by mixing calsequestrin equilibrated with calcium with calcium-free solutions in a stopped-flow system. In parallel, we measured the kinetics of the intrinsic fluorescence changes that take place following calcium dissociation from calsequestrin. We found that at 25ºC calcium dissociation was 10-fold faster for calsequestrin attached to junctional membranes (k = 109 s-1) than in solution. These results imply that calcium dissociation from calsequestrin in vivo is not rate limiting during excitation-contraction coupling. In addition, we found that the intrinsic fluorescence decrease for calsequestrin in solution or forming part of junctional membranes was significantly slower than the rates of calcium dissociation. The kinetics of intrinsic fluorescence changes had two components for calsequestrin associated to junctional membranes and only one for calsequestrin in solution; the faster component was 8-fold faster (k = 54.1 s-1) than the slower component (k = 6.9 s-1), which had the same k value as for calsequestrin in solution. These combined results suggest that the presence of calsequestrin at high concentrations in a restricted space, such as when bound to the junctional membrane, accelerates calcium dissociation and the resulting structural changes, presumably as a result of cooperative molecular interactions.
author	BELTRÁN,MARIANELA BARRIENTOS,GENARO HIDALGO,CECILIA
author_facet	BELTRÁN,MARIANELA BARRIENTOS,GENARO HIDALGO,CECILIA
author_sort	BELTRÁN,MARIANELA
title	Fast kinetics of calcium dissociation from calsequestrin
title_short	Fast kinetics of calcium dissociation from calsequestrin
title_full	Fast kinetics of calcium dissociation from calsequestrin
title_fullStr	Fast kinetics of calcium dissociation from calsequestrin
title_full_unstemmed	Fast kinetics of calcium dissociation from calsequestrin
title_sort	fast kinetics of calcium dissociation from calsequestrin
publisher	Sociedad de Biología de Chile
publishDate	2006
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602006000300011
work_keys_str_mv	AT beltranmarianela fastkineticsofcalciumdissociationfromcalsequestrin AT barrientosgenaro fastkineticsofcalciumdissociationfromcalsequestrin AT hidalgocecilia fastkineticsofcalciumdissociationfromcalsequestrin
_version_	1718441406305927168

Fast kinetics of calcium dissociation from calsequestrin

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