Myosin is best associated with which function?

• A. Thick filaments of muscle fibers
• B. Muscle contraction
• C. Hormone synthesis
• D. Oxygen transport

Answer: (B)

Myosin is the motor protein that drives muscle movement. It sits in the thick filaments of muscle fibers and, using energy from ATP, its heads bind to actin and pull, causing the sarcomere to shorten in a sliding filament process. This cross-bridge cycling is the mechanism behind muscle contraction, so the function most closely linked to myosin is muscle contraction. Hormone synthesis and oxygen transport aren’t roles of myosin, and while myosin is a component of thick filaments, the defining action it performs in muscle tissue is generating contraction.