Using Mice,a Biologist Studying the Cycle of Protein Interactions in Muscle

Multiple Choice

Using mice,a biologist studying the cycle of protein interactions in muscle contraction has induced a mutation in one of the genes encoding proteins involved in this cycle.She finds that the muscle fibers expressing this mutation are not able to contract.Upon further investigation,she finds that calcium release into the sarcoplasm is normal,and calcium binding to protein filaments is normal.Which hypothesis could explain this mutation?

A) The mutation occurs at the site on actin where myosin binds.
B) The mutation occurs in a region of tropomyosin that undergoes conformational change to expose the myosin-binding site on actin.
C) The mutation occurs in the myosin tail region,preventing titin binding to myosin.
D) The mutation occurs in myosin and prevents release of inorganic phosphate from the ATP binding site.
E) All of the above