[3H]ryanodine as a probe of changes in the functional state of the Ca(2+)-release channel in malignant hyperthermia
The defect in malignant hyperthermia (MH) alters the binding of [3H]ryanodine to the Ca(2+)-release channel by increasing its apparent affinity for the binding site. In sarcoplasmic reticulum (SR) membranes from both normal and mutant pigs the apparent Kd is dependent on a number of parameters. Aden...
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Published in | The Journal of biological chemistry Vol. 267; no. 10; pp. 6702 - 6709 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
American Society for Biochemistry and Molecular Biology
05.04.1992
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Subjects | |
Online Access | Get full text |
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Summary: | The defect in malignant hyperthermia (MH) alters the binding of [3H]ryanodine to the Ca(2+)-release channel by increasing
its apparent affinity for the binding site. In sarcoplasmic reticulum (SR) membranes from both normal and mutant pigs the
apparent Kd is dependent on a number of parameters. Adenosine 5'-(beta,gamma-methylene)triphosphate, ionic strength, and Ca2+
each increase the apparent affinity of the binding site for [3H]ryanodine. Equilibrium and kinetic evaluation of the binding
of [3H]ryanodine to these membranes demonstrates that the MH defect in pigs increases the apparent affinity of the membranes
for [3H]ryanodine by increasing the amount of high affinity relative to low affinity binding sites. Both the association and
dissociation of [3H]ryanodine with all three types of membranes (normal, heterozygous MH, homozygous MH) are characterized
by two or more components, with the relative ratios of these components altered by the MH defect. These findings suggest that
the observed Kd is the weighted average of the binding of ryanodine to two or more interconvertible states of the channel.
Dilution of [3H]ryanodine bound to normal membranes at high Ca2+ into low Ca2+ solutions enhances the rate of dissociation.
This conversion occurs to a much lesser extent with MH membranes, suggesting that the MH defect may alter the rate at which
the high affinity form of the protein converts to the low affinity form. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(19)50483-5 |