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The ability of myosin to interact with actin is regulated by the binding of?
Huntingp5
Ca2+ to troponin
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∙ 15y ago
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What is the role of tropomyosin in muscles?
Tropomyosin is the thick filament of a muscle sarcomere. It lines the span of 7 G-actin monomers along the grooves of the F-actin filament. Troponin is a trimer that consists of subunits TN-C, TN-I and TN-T. Troponin is attached to tropomyosin and its function is involved in muscle contraction. In a powerstroke of a muscle contraction you have TN-I blocking the myosin head from attaching to the myosin binding site on the actin filament. This is the resting state. When you contract your muscles, calcium is released and attaches to TN-C. This produces a conformational change that moves TN-I away from the myosin head. In turn the myosin binds to the myosin binding site. On the myosin head there is a myosin ATPase that hydrolyzes an ATP which provides the energy for the head to bend 45 degrees. This is the powerstroke that produces muscle contraction. Another ATP molecule will enter in and release the myosin head and calcium is pumped back into the sarcoplasmic reticulum. The resting state is restored!
Does myosin have the ability to swivel when powered by ATP?
Yes...ATP causes myosin to detach from actin. Then, Hydrolysis of ATP, which results in ADP and P, causes conformational change in myosin head to swivel or pivot about its axis and then weakly bind to an actin filament. Once the myosin head binds, a conformational change in the myosin head will cause the P to leave (the ADP is still stuck on). The leaving of the P causes the power stroke or "the pulling of the actin filament/rowing stroke". ADP then leaves and the myosin is now back at its original state.
What are the thick protein filaments in the cell made of?
The thick filament is composed of the myosin molecule. The thin filament is composed of the actin molecule. Flexing the head of myosin provides the powerstroke.
What happens when calcium ions bind to troponin?
When Ca2+ ions are released from the sarcoplasmic reticulum, They combine with troponin, and this cause the tropomyosin threads to shift their position
Which proteins found myofilaments contains the cross bridge?
The two muscle filaments are Myosin and Actin. Myosin is the thicker of the two. When a muscle contracts, a hook like particle extends off the myosin and grabs the actin pulling it in causing the contraction/ tension of the muscle
Binding of the myosin heads sequentially prevents what?
myosin crossbridge binding
The binding of calcium to which molecule causes the myosin binding sites to be exposed?
Troponin binds to the Calcium ions to expose the actin to the myosin heads.
How do proteins actin and myosin interact to make a muscle contract?
Myosin and Actin
What specifically is cross bridge?
myosin binding to actin
What immediately follows the binding of ATP to the myosin head?
The myosin head pivots, moving the actin strand.
What protein interact in muscle cells?
Actin and myosin interact in muscle cells.
What does binding of the myosin heads sequentially prevent?
lengthening of the sacromere.
What protein shields the myosin-binding site preventing contraction from happening at rest?
ATP entering myosin head
What 2 proteins make up the mass of a muscle cell?
Actin and myosin interact in muscle cells.
Which event causes cross bridge detachment?
ATP binding to the myosin head
What molecule has a binding site for myosin heads?
Myosin heads bind to the actin binding site, and also has a part where ATP binds
What muscle cell protein covers the myosin binding sites on actin fimlaments?
tropomyosin
