The hydrolysis of ATP causes myosin to immediately (Select one) : a. bind more tightly to the actin (rigor). b. rotate into a position (cocked) to bind to actin. c. swivel, moving the actin molecule. d. release from the actin. e. release ADP.

Question

Biology

Davin Gregory

7 February, 21:18

The hydrolysis of ATP causes myosin to immediately (Select one) : a. bind more tightly to the actin (rigor). b. rotate into a position (cocked) to bind to actin. c. swivel, moving the actin molecule. d. release from the actin. e. release ADP.

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Answers (1)

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Valerie Cross · Answer 1

b. Rotate into a position (cocked) to bind to actin.

Explanation:

The cycle starts with the myosin strongly united to the actin (in absence of ATP). The union of ATP dissociates the myosin from the actin and the ATP hydrolysis induces a conformational change in the myosin. This change affects the neck region of the myosin, which acts like a lever arm displacing the head group of the myosin. The ADP and phosphate stay united to the myosin head, which unites to the actin filament in a new position, liberating the phosphate and releasing ADP. This way, the myosin head adopts again its initial conformation.