Question

you have designed a drug that is supposed to bind to the myosin binding sites on actin. you inject it into a relaxed muscle, but find that none of the drug bound. which of the following explains why? multiple choice there are no myosin binding sites on actin. troponin molecules are covering myosin binding sites on actin. the myosin binding sites are covered by atp. the myosin binding sites on actin are covered by tropomyosin. none of the choices are correct.

Explanation:

In a relaxed muscle, tropomyosin covers the myosin - binding sites on actin, preventing myosin from binding. This is why the drug couldn't bind to the myosin - binding sites on actin. Troponin is involved in the regulation but does not directly cover the sites. ATP is involved in the energy - related processes of muscle contraction, not in covering the binding sites. And there are myosin - binding sites on actin.

Answer:

The myosin binding sites on actin are covered by tropomyosin