Journal article
Analysis of the Molecular Pathogenesis of Cardiomyopathy-Causing cTnT Mutants I79N, ΔE96, and ΔK210
Biophysical journal, Vol.104(9), pp.1979-1988
05/07/2013
DOI: 10.1016/j.bpj.2013.04.001
PMCID: PMC3647163
PMID: 23663841
Abstract
Three troponin T (TnT) mutants that cause hypertrophic, restrictive, and dilated cardiomyopathy (I79N, ΔE96, and ΔK210, respectively), were examined using the thin-filament extraction/reconstitution technique. Effects of Ca
2+
, ATP, phosphate, and ADP concentrations on force and its transients were studied at 25°C. Maximal Ca
2+
tension (
T
HC
) and Ca
2+
-activatable tension (
T
act
), respectively, were similar among I79N, ΔE96, and WT, whereas ΔK210 led to a significantly lower
T
HC
(∼20% less) and
T
act
(∼25% less) than did WT. In pCa solution containing 8 mM Pi and ionic strength adjusted to 200 mM, the Ca
2+
sensitivity (pCa
50
) of I79N (5.63 ± 0.02) and ΔE96 (5.60 ± 0.03) was significantly greater than that of WT (5.45 ± 0.04), but the pCa
50
of ΔK210 (5.54 ± 0.04) remained similar to that of WT. Five equilibrium constants were deduced using sinusoidal analysis. All three mutants showed significantly lower
K
0
(ADP association constant) and larger
K
4
(equilibrium constant of force generation step) relative to the corresponding values for WT. I79N and ΔK210 were associated with a
K
2
(equilibrium constant of cross-bridge detachment step) significantly lower than that of ΔE96 and WT. These results demonstrated that at pCa 4.66, the force/cross-bridge is ∼18% less in I79N and ∼41% less in ΔK210 than that in WT. These results indicate that the molecular pathogenesis of the cardiac TnT mutation-related cardiomyopathies is different for each mutation.
Details
- Title: Subtitle
- Analysis of the Molecular Pathogenesis of Cardiomyopathy-Causing cTnT Mutants I79N, ΔE96, and ΔK210
- Creators
- Fan Bai - Departments of Anatomy and Cell Biology, and Internal Medicine, The University of Iowa, Iowa City, IowaHannah M Caster - Departments of Anatomy and Cell Biology, and Internal Medicine, The University of Iowa, Iowa City, IowaJose R Pinto - Department of Biomedical Sciences, The Florida State University, College of Medicine, Tallahassee, FloridaMasataka Kawai - Departments of Anatomy and Cell Biology, and Internal Medicine, The University of Iowa, Iowa City, Iowa
- Resource Type
- Journal article
- Publication Details
- Biophysical journal, Vol.104(9), pp.1979-1988
- Publisher
- The Biophysical Society
- DOI
- 10.1016/j.bpj.2013.04.001
- PMID
- 23663841
- PMCID
- PMC3647163
- ISSN
- 0006-3495
- eISSN
- 1542-0086
- Language
- English
- Date published
- 05/07/2013
- Academic Unit
- Anatomy and Cell Biology; Internal Medicine
- Record Identifier
- 9984025691402771
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