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Anonymous
Anonymous asked in Science & MathematicsZoology · 1 decade ago

What is the structure of thin filament (composed of actin, troponin & tropomyosin) of myofibril of muscle cell?

Update:

I am not talking about the structure of whole myofibril. I just want to know the arrangement of actin, troponin and tropomyosin molecules (or chains of molecules) in the thin filament on myofibril. [EDITED AFTER READING THE FIRST ANSWER]

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  • dakini
    Lv 4
    1 decade ago
    Favorite Answer

    Wikipedia knows a lot:

    "...In muscle, actin is the major component of thin filaments, which, together with the motor protein myosin (which forms thick filaments), are arranged into actomyosin myofibrils. These fibrils comprise the mechanism of muscle contraction. Using the hydrolysis of ATP for energy, myosin heads undergo a cycle during which they attach to thin filaments, exerting a tension, and then depending on the load, perform a power stroke that causes the thin filaments to slide past, shortening the muscle..."

    Further description and figeres about the molecular structure in:

    http://en.wikipedia.org/wiki/Actin

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  • 1 decade ago

    Actin is like a pair of pearl necklaces twisted around eachother. The Tropomyosin is like a cable lying alongside the necklaces (covering binding sites for myosin). Troponin is a globular protein made of three bits which can shove the tropomyosin to one side to reveal binding sites for myosin.

    Check out these diagrams on the web:

    http://www.angelbrady.com/images/slidingfilscroll....

    http://www.ucl.ac.uk/~sjjgsca/Muscleslidingfilamen...

    http://www.ucl.ac.uk/~sjjgsca/MuscleSlidingfilamen...

    Source(s): Me, a teacher!
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