ArticleThe Journal of physiology2009
Calcium- and myosin-dependent changes in troponin structure during activation of heart muscle.
Article in The Journal of physiology, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 66 papers.
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Who cites it
66 citing papers in PubMed, 101 citations in OpenAlex.
- Temperature dependence of activation of thick and thin filaments in skeletal and cardiac muscles.Journal of muscle research and cell motility · 2026Review
- Modulation of striated-muscle contractility by a high-affinity myosin-targeting peptide.Biophysical journal · 2025Article
- Myosin-actin crossbridge independent sarcomere length induced CaJournal of molecular and cellular cardiology · 2025Article
- The Impact of Calcium Overload on Cellular Processes: Exploring Calcicoptosis and Its Therapeutic Potential in Cancer.International journal of molecular sciences · 2024Review
- Structural changes in troponin during activation of skeletal and heart muscle determined in situ by polarised fluorescence.Biophysical reviews · 2024Review
- Using a Failing Human Ventricular Cardiomyocyte Model to Re-Evaluate CaBiomolecules · 2024Article
- Local Control Model of a Human Ventricular Myocyte: An Exploration of Frequency-Dependent Changes and Calcium Sparks.Biomolecules · 2023Article
- The force of the myosin motor sets cooperativity in thin filament activation of skeletal muscles.Communications biology · 2022Article
- Of mitochondrion and COVID-19.Journal of enzyme inhibition and medicinal chemistry · 2021Review
- The regulatory light chain mediates inactivation of myosin motors during active shortening of cardiac muscle.Nature communications · 2021Article
- Novel insights into sarcomere regulatory systems control of cardiac thin filament activation.The Journal of general physiology · 2021Article
- Biophysically detailed mathematical models of multiscale cardiac active mechanics.PLoS computational biology · 2020Article
- Cardiac myosin regulatory light chain kinase modulates cardiac contractility by phosphorylating both myosin regulatory light chain and troponin I.The Journal of biological chemistry · 2020Article
- Cycling Cross-Bridges Contribute to Thin Filament Activation in Human Slow-Twitch Fibers.Frontiers in physiology · 2020Article
- Sarcomere length-dependent effects on CaThe Journal of general physiology · 2019Article
- CaBiophysical journal · 2018Article
- Structural and functional effects of myosin-binding protein-C phosphorylation in heart muscle are not mimicked by serine-to-aspartate substitutions.The Journal of biological chemistry · 2018Article
- Hypertrophic cardiomyopathy mutation R58Q in the myosin regulatory light chain perturbs thick filament-based regulation in cardiac muscle.Journal of molecular and cellular cardiology · 2018Article
- Omecamtiv mercabil and blebbistatin modulate cardiac contractility by perturbing the regulatory state of the myosin filament.The Journal of physiology · 2018Article
- Article
6 more citing papers are in PubMed but not listed here.
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Authors and funding
3 authors at 2 institutions in 1 country.
Funding
Abstract
Each heartbeat is triggered by a pulse of intracellular calcium ions which bind to troponin on the actin-containing thin filaments of heart muscle cells, initiating a change in filament structure that allows myosin to bind and generate force. We investigated the molecular mechanism of calcium regulation in demembranated trabeculae from rat ventricle using polarized fluorescence from probes on troponin C (TnC). Native TnC was replaced by double-cysteine mutants of human cardiac TnC with bifunctional rhodamine attached along either the C helix, adjacent to the regulatory Ca(2+)-binding site, or the E helix in the IT arm of the troponin complex. Changes in the orientation of both troponin helices had the same steep Ca(2+) dependence as active force production, with a Hill coefficient (n(H)) close to 3, consistent with a single co-operative transition controlled by Ca(2+) binding. Complete inhibition of active force by 25 microM blebbistatin had very little effect on the Ca(2+)-dependent structural changes and in particular did not significantly reduce the value of n(H). Binding of rigor myosin heads to thin filaments following MgATP depletion in the absence of Ca(2+) also changed the orientation of the C and E helices, and addition of Ca(2+) in rigor produced further changes characterized by increased Ca(2+) affinity but with n(H) close to 1. These results show that, although myosin binding can switch on thin filaments in rigor conditions, it does not contribute significantly under physiological conditions. The physiological mechanism of co-operative Ca(2+) regulation of cardiac contractility must therefore be intrinsic to the thin filaments.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.