Which molecule causes the myosin binding sites to be exposed?

The calcium ions bind to regulatory proteins on the actin filaments, changing both their shape and their position on the actin filaments. This action allows myosin receptor sites on the thin actin filaments to become exposed. The myosin heads attach to the myosin binding sites on the actin filaments.

1. What protein has to be moved to expose the myosin binding sites on actin?
2. When the binding site is exposed actin binds to what?
3. When binding sites on actin are exposed what happens to myosin?
4. What causes the repositioning of the myosin head to its high energy conformation?
5. Which molecule has a binding site for calcium ions?
6. What causes the myosin binding sites on actin to be exposed?
7. What happens to Pi and ADP when myosin binds?
8. Where is the myosin binding site located?
9. How are binding sites on actin exposed quizlet?
10. What causes the ATP to bind to the myosin head?
11. What molecule is the myosin head bound to?
12. What has to bind to troponin before the active binding sites are exposed?
13. Which molecule contains a binding site for the attachment of myosin heads quizlet?
14. Which molecule blocks the active sites of actin preventing interaction with myosin?
15. What molecule binds with the thin filament and which molecule binds with the thick filament?
16. What molecule creates the power stroke when its released?
17. Which of the following molecules covers the active sites on the G actin molecule when the muscle fiber is relaxed?

What protein has to be moved to expose the myosin binding sites on actin?

Muscle contraction is very tightly regulated. Tropomyosin binds actin filaments and covers the myosin binding sites. Troponin interacts with tropomyosin. When stimulated by calcium, troponin undergoes a conformational change that moves the tropomyosin and exposes the myosin binding sites on the actin protein.

When the binding site is exposed actin binds to what?

Skeletal Muscle Contraction

Figure 4: (a) The active site on actin is exposed as calcium binds to troponin. (b) The myosin head is attracted to actin, and myosin binds actin at its actin-binding site, forming the cross-bridge.

When binding sites on actin are exposed what happens to myosin?

Specifically, troponin (the smaller protein) shifts the position of tropomyosin and moves it away from the myosin-binding sites on actin, effectively unblocking the binding site (Figure 5). Once the myosin-binding sites are exposed, and if sufficient ATP is present, myosin binds to actin to begin cross-bridge cycling.

What causes the repositioning of the myosin head to its high energy conformation?

The “power stroke” of the myosin head that causes the movement of the thin filament. ... The hydrolysis of ATP which re-energizes and repositions the myosin molecule (returns it to the high energy conformation).

Which molecule has a binding site for calcium ions?

The calcium ions bind to the troponin, changing the shape of the troponin-tropomyosin complex such that the actin binding sites are uncovered. As soon as myosin binds to actin, the cocked head of myosin releases sliding the actin fiber.

What causes the myosin binding sites on actin to be exposed?

The calcium ions bind to regulatory proteins on the actin filaments, changing both their shape and their position on the actin filaments. This action allows myosin receptor sites on the thin actin filaments to become exposed.

What happens to Pi and ADP when myosin binds?

ADP and Pi remain attached; myosin is in its high energy configuration. ... Once myosin binds to the actin, the P_i is released, and the myosin undergoes a conformational change to a lower energy state. As myosin expends the energy, it moves through the “power stroke,” pulling the actin filament toward the M-line.

Where is the myosin binding site located?

The location of the myosin binding is an extended region encompassing the junction of domains 3/4 and domain 4a (residues 622-714, human; 566-657, chicken gizzard).

How are binding sites on actin exposed quizlet?

How are binding sites on actin exposed? Contractile proteins from the transverse tubules attach to the binding sites on actin to fold them into their active configuration. Calcium ions attach to troponin which slides tropomyosin off binding sites on actin.

What causes the ATP to bind to the myosin head?

ATP first binds to myosin, moving it to a high-energy state. The ATP is hydrolyzed into ADP and inorganic phosphate (P_i) by the enzyme ATPase. The energy released during ATP hydrolysis changes the angle of the myosin head into a “cocked” position, ready to bind to actin if the sites are available.

What molecule is the myosin head bound to?

The motion of muscle shortening occurs as myosin heads bind to actin and pull the actin inwards. This action requires energy, which is provided by ATP. Myosin binds to actin at a binding site on the globular actin protein.

What has to bind to troponin before the active binding sites are exposed?

Tropomyosin binds to troponin to form a troponin-tropomyosin complex. The troponin-tropomyosin complex prevents the myosin “heads” from binding to the active sites on the actin microfilaments.

Which molecule contains a binding site for the attachment of myosin heads quizlet?

Troponin controls the position of tropomyosin on the thin filament, enabling myosin heads to bind to the active sites on actin. Troponin hydrolyzes ATP, which provides the energy necessary for cross bridges to form.

Which molecule blocks the active sites of actin preventing interaction with myosin?

Tropomyosin blocks myosin binding sites on actin molecules, preventing cross-bridge formation, which prevents contraction in a muscle without nervous input. The protein complex troponin binds to tropomyosin, helping to position it on the actin molecule.

What molecule binds with the thin filament and which molecule binds with the thick filament?

In the sarcomere, myosin II is assembled into thick filaments, which cyclically bind to the actin-containing thin filaments in the presence of adenosine triphosphate (ATP) to generate force. However, access to actin is modulated by the control proteins troponin (Tn) and tropomyosin (Tm).

What molecule creates the power stroke when its released?

The power stroke occurs when ATP is hydrolyzed to ADP and phosphate. The power stroke occurs when ADP and phosphate dissociate from the myosin head. The power stroke occurs when ADP and phosphate dissociate from the actin active site.

Which of the following molecules covers the active sites on the G actin molecule when the muscle fiber is relaxed?

Contraction of a muscle fiber requires that the myosin heads in the thick filament bind to active sites on G-actin molecules within the thin filaments. When the muscle fiber is in a relaxed state, the tropomyosin molecules cover these active sites, preventing interaction between thick filaments and thin filaments.