ArticleBiophysical journal1996
The effect of partial extraction of troponin C on the elementary steps of the cross-bridge cycle in rabbit psoas muscle fibers.
Article in Biophysical journal, 1996. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 19 papers.
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19 citing papers in PubMed, 22 citations in OpenAlex.
- Phosphate has dual roles in cross-bridge kinetics in rabbit psoas single myofibrils.The Journal of general physiology · 2021Article
- Development of apical hypertrophic cardiomyopathy with age in a transgenic mouse model carrying the cardiac actin E99K mutation.Journal of muscle research and cell motility · 2017Article
- Using baculovirus/insect cell expressed recombinant actin to study the molecular pathogenesis of HCM caused by actin mutation A331P.Journal of molecular and cellular cardiology · 2014Article
- Analysis of the molecular pathogenesis of cardiomyopathy-causing cTnT mutants I79N, ΔE96, and ΔK210.Biophysical journal · 2013Article
- ATP binding and cross-bridge detachment steps during full Ca²⁺ activation: comparison of myofibril and muscle fibre mechanics by sinusoidal analysis.The Journal of physiology · 2012Article
- Article
- Correlation between cross-bridge kinetics obtained from Trp fluorescence of myofibril suspensions and mechanical studies of single muscle fibers in rabbit psoas.Journal of muscle research and cell motility · 2011Article
- Enhanced active cross-bridges during diastole: molecular pathogenesis of tropomyosin's HCM mutations.Biophysical journal · 2011Article
- Large-scale models reveal the two-component mechanics of striated muscle.International journal of molecular sciences · 2008Article
- Force transients and minimum cross-bridge models in muscular contraction.Journal of muscle research and cell motility · 2007Review
- Use of thin filament reconstituted muscle fibres to probe the mechanism of force generation.Journal of muscle research and cell motility · 2006Review
- Role of the N-terminal negative charges of actin in force generation and cross-bridge kinetics in reconstituted bovine cardiac muscle fibres.The Journal of physiology · 2005Article
- The effect of tropomyosin on force and elementary steps of the cross-bridge cycle in reconstituted bovine myocardium.The Journal of physiology · 2004Article
- What do we learn by studying the temperature effect on isometric tension and tension transients in mammalian striated muscle fibres?Journal of muscle research and cell motility · 2003Review
- Characterization of the cross-bridge force-generating step using inorganic phosphate and BDM in myofibrils from rabbit skeletal muscles.The Journal of physiology · 2002Article
- Elementary steps of the cross-bridge cycle in bovine myocardium with and without regulatory proteins.Biophysical journal · 2002Article
- Effect of temperature on elementary steps of the cross-bridge cycle in rabbit soleus slow-twitch muscle fibres.The Journal of physiology · 2001Article
- Does thin filament compliance diminish the cross-bridge kinetics? A study in rabbit psoas fibers.Biophysical journal · 1999Article
- Troponin C modulates the activation of thin filaments by rigor cross-bridges.Biophysical journal · 1997Article
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Authors and funding
4 authors at 1 institution in 1 country.
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Abstract
The elementary steps of the cross-bridge cycle in which troponin C (TnC) was partially extracted were investigated by sinusoidal analysis in rabbit psoas muscle fibers. The effects of MgATP and phosphate on the rate constants of exponential processes were studied at 200 mM ionic strength, pCa 4.20, pH 7.00, and at 20 degrees C. The results were analyzed with the following cross-bridge scheme: [formula: see text] where A is actin, M is myosin, S is MgATP, D is MgADP, and P is phosphate (Pi). When TnC was extracted so that the average remaining tension was 11% (range 8-15%), K1 (MgATP association constant) increased to 7x, k2 (rate constant of cross-bridge detachment) increased to 1.55x, k-2 (reversal of detachment) decreased to 0.27x, and K2 (= k2/k-2: equilibrium constant of cross-bridge detachment) increased to 6.6x, k4 (rate constant of force generation) decreased to 0.4x, k-4 (reversal of force generation) increased to 2x, K4 (= k4/k-4) decreased to 0.17x, and K5 (Pi association constant) did not change. The activation factor alpha, which represents the fraction of cross-bridges participating in the cycling, decreased from 1 to 0.14 with TnC extraction. The fact that K1 increased with TnC extraction implies that the condition of the thin filament modifies the contour of the substrate binding site on the myosin head and is consistent with the Fenn effect. The fact that alpha decreased to 0.14 is consistent with the steric blocking mechanism (recruitment hypothesis) and indicates that some of the cross-bridges disappear from the active cycling pool. The fact that the equilibrium constants changed is consistent with the cooperative activation mechanism (graded activation hypothesis) among thin-filament regulatory units that consist of troponin (TnC, Tnl, TnT), tropomyosin, and seven actin molecules, and possibly include cross-bridges.
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