ArticleProceedings of the National Academy of Sciences of the United States of America2006
Structural changes in troponin in response to Ca2+ and myosin binding to thin filaments during activation of skeletal muscle.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2006. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 22 papers.
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Who cites it
22 citing papers in PubMed, 42 citations in OpenAlex.
- Subsarcomeric regulation of thin and thick filaments in skeletal muscle myofibrils.Proceedings of the National Academy of Sciences of the United States of America · 2026Article
- Structural changes in troponin during activation of skeletal and heart muscle determined in situ by polarised fluorescence.Biophysical reviews · 2024Review
- Activation of skeletal muscle is controlled by a dual-filament mechano-sensing mechanism.Proceedings of the National Academy of Sciences of the United States of America · 2023Article
- Sarcomere dynamics revealed by a myofilament integrated FRET-based biosensor in live skeletal muscle fibers.Scientific reports · 2022Article
- Cycling Cross-Bridges Contribute to Thin Filament Activation in Human Slow-Twitch Fibers.Frontiers in physiology · 2020Article
- Constructing a structural model of troponin using site-directed spin labeling: EPR and PRE-NMR.Biophysical reviews · 2019Review
- Regulation of Contraction by the Thick Filaments in Skeletal Muscle.Biophysical journal · 2017Review
- Thick filament mechano-sensing is a calcium-independent regulatory mechanism in skeletal muscle.Nature communications · 2016Article
- Toward Understanding the Molecular Bases of Stretch Activation: A STRUCTURAL COMPARISON OF THE TWO TROPONIN C ISOFORMS OF LETHOCERUS.The Journal of biological chemistry · 2016Article
- The Sick and the Weak: Neuropathies/Myopathies in the Critically Ill.Physiological reviews · 2015Review
- Structures of the troponin core domain containing the cardiomyopathy-causing mutants studied by small-angle X-ray scattering.Biophysics and physicobiology · 2015Article
- Structural dynamics of troponin during activation of skeletal muscle.Proceedings of the National Academy of Sciences of the United States of America · 2014Article
- Orientation and rotational motions of single molecules by polarized total internal reflection fluorescence microscopy (polTIRFM).Cold Spring Harbor protocols · 2012Article
- HD exchange and PLIMSTEX determine the affinities and order of binding of Ca2+ with troponin C.Biochemistry · 2011Article
- Switch action of troponin on muscle thin filament as revealed by spin labeling and pulsed EPR.The Journal of biological chemistry · 2010Article
- Troponin regulatory function and dynamics revealed by H/D exchange-mass spectrometry.The Journal of biological chemistry · 2010Article
- X-ray fiber diffraction modeling of structural changes of the thin filament upon activation of live vertebrate skeletal muscles.Biophysics (Nagoya-shi, Japan) · 2010Article
- Calcium- and myosin-dependent changes in troponin structure during activation of heart muscle.The Journal of physiology · 2009Article
- Modulation of troponin C affinity for the thin filament by different cross-bridge states in skinned skeletal muscle fibers.Pflugers Archiv : European journal of physiology · 2008Article
- Structural basis for the regulation of muscle contraction by troponin and tropomyosin.Journal of molecular biology · 2008Article
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Authors and funding
3 authors at 2 institutions in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Contraction of skeletal and cardiac muscle is regulated by Ca2+ -dependent structural changes in troponin that control the interaction between myosin and actin. We measured the orientations of troponin domains in skeletal muscle fibers using polarized fluorescence from bifunctional rhodamine probes on the C and E helices of troponin C. The C helix, in the regulatory head domain, tilts by approximately 30 degrees when muscle is activated in physiological conditions, with a Ca2+ -sensitivity similar to that of active force. Complete inhibition of active force did not affect C-helix orientation, and binding of rigor myosin heads did not affect its orientation at saturating [Ca2+]. The E helix, in the IT arm of troponin, tilted by approximately 10 degrees on activation, and this was reduced to only 3 degrees when active force was inhibited. Binding of rigor myosin heads produced a larger tilt of the E helix. Thus, in situ, the regulatory head acts as a pure Ca2+ -sensor, whereas the IT arm is primarily sensitive to myosin head binding. The polarized fluorescence data from active muscle are consistent with an in vitro structure of the troponin core complex in which the D and E helices of troponin C are collinear. The present data were used to orient this structure in the fiber and suggest that the IT arm is at approximately 30 degrees to the filament axis in active muscle. In relaxed muscle, the IT arm tilts to approximately 40 degrees but the D/E helix linker melts, allowing the regulatory head to tilt through a larger angle.
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