One form of muscle disease is caused by a mutant myosin allele. It prevents myosin from binding to other myosin molecules, thus preventing contraction. Suggest why.

Sarcomeres are formed of myosin and actin filaments which are interleaved. If myosin cannot bind to each other then thick filaments cannot be formed. Thus, there is nothing to anchor myosin so actin cannot be pulled during contraction and the sarcomere cannot shorten. Additionally, when the myosin heads rotate during the power stroke, generating the force required to pull actin, the myosin itself will move instead.

JW

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