troponin

(noun)

a complex of three regulatory proteins that is integral to muscle contraction in skeletal and cardiac muscle, or any member of this complex

Related Terms

Examples of troponin in the following topics:

  • Regulatory Proteins

    • Tropomyosin and troponin prevent myosin from binding to actin while the muscle is in a resting state.
    • The protein complex troponin binds to tropomyosin, helping to position it on the actin molecule.
    • If present, calcium ions bind to troponin, causing conformational changes in troponin that allow tropomyosin to move away from the myosin-binding sites on actin.
    • Calcium then binds to troponin, causing the troponin to change shape and remove the tropomyosin from the binding sites.
    • Describe how calcium, tropomyosin, and the troponin complex regulate the binding of actin by myosin

  • Statistical Literacy

    • Cardiac troponins are markers of myocardial damage.
    • The levels of troponin in subjects with and without signs of right ventricular strain in the electrocardiogram were compared in the experiment described here: http://www.bmj.com/content/326/7384/312.
    • The troponin concentration in patients with signs of right ventricular strain was higher (median = 0.03 ng/ml) than in patients without right ventricular strain (median < 0.01 ng/ml), p<0.001.

  • Mechanism and Contraction Events of Cardiac Muscle Fibers

    • Calcium in the cytoplasm then binds to cardiac troponin-C, which moves the troponin complex away from the actin binding site.
    • This removal of the troponin complex frees the actin to be bound by myosin and initiates contraction.
    • Intracellular calcium is then removed by the sarcoplasmic reticulum, dropping intracellular calcium concentration, returning the troponin complex to its inhibiting position on the active site of actin, and effectively ending contraction as the actin filaments return to their initial position, relaxing the muscle.

  • ATP and Muscle Contraction

    • The muscle contraction cycle is triggered by calcium ions binding to the protein complex troponin, exposing the active-binding sites on the actin.

  • Muscle Fatigue

    • Contraction of a muscle requires Ca+ ions to interact with troponin exposing the actin binding site to the myosin head.
    • Accumulation of metabolites from these reactions other than lactic acid such as Mg2+ ions or reactive oxygen species can also induce fatigue by interfering with the release of Ca+ ions from the sarcoplasmic reticulum or through reduction in the sensitivity of troponin to Ca+.

  • Excitation–Contraction Coupling

    • The action potential triggers the sarcoplasmic reticulum to release of Ca2+, which activate troponin and stimulate muscle contraction.

  • Skeletal Muscle Fibers

    • Thin filaments are composed predominately of actin, tropomyosin, and troponin.