Linked Life Data

1898095

Source:http://linkedlifedata.com/resource/pubmed/id/1898095

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1991-10-23
pubmed:abstractText
We have examined ryanodine binding to its receptor (RR) and compared its effect on Ca2+ release to the Ca2+ release triggered by Ca2+ plus ATP, using vesicular fragments of junctional terminal cisternae (JTC) obtained from skeletal muscle. Ryanodine binding is slow (taking hours or days to complete) and is highly temperature (Q10 = 4) and Ca2+ dependent. At equilibrium, the extent of binding increases as the concentration of ryanodine is raised above 10(-9) M, exhibiting negative cooperativity and reaching the stoichiometry of the 560,000-Da RR chains near 10(-5) M ryanodine. The specificity of the high affinity binding is demonstrated by competitive binding of ryanodine analogs. Kinetic studies using rapid filtration show that, in the absence of ryanodine, rapid (k = 15 s-1) release of Ca2+ follows a triggering exposure of loaded JTC vesicles to perfusion media containing Ca2+ plus ATP. Induction of this release has no lag period and displays minimal temperature dependence. In contrast, prolonged exposure of JTC vesicles to low (10(-7) M) ryanodine concentrations changes the JTC to a state permitting slow (k = 1 s-1) release of Ca2+ even in the absence of the Ca2+ plus ATP trigger. Higher (greater than microM) concentrations of ryanodine do not allow any Ca2+ release and prevent even the release normally triggered by Ca2+ plus ATP. Our data suggest that ryanodine binds to the open state of the tetrameric RR, inducing protein conformational changes and altered oligomeric interactions. Binding of the first molecule of ryanodine to one of the four binding sites on the receptor produces a partially closed and low conductance state of the Ca2+ release channel and reduces the ryanodine binding affinity of the remaining sites. Ryanodine occupancy of all four binding sites on the receptor completes closure of the Ca2+ channel and blocks the triggering action of Ca2+ plus ATP. The tetrameric association of the RR chains is demonstrated by crosslinking with bifunctional reagents, generating crosslinked tetramers that retain ryanodine binding and Ca2+ release functions.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0003-9861
pubmed:author
pubmed:issnType
Print
pubmed:volume
290
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
239-47
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Interdependence of ryanodine binding, oligomeric receptor interactions, and Ca2+ release regulation in junctional sarcoplasmic reticulum.
pubmed:affiliation
Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore 21201-1596.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't