Final answer:
Type II myosin motors are involved in muscle contraction by forming large bipolar filaments that pull actin filaments towards the M line of the sarcomere during the power stroke, using ATP-derived energy.
Step-by-step explanation:
Type II myosin motor proteins are known for their involvement in muscle contraction, specifically within skeletal and cardiac muscles. These proteins form large, bipolar filaments and are responsible for pulling actin filaments toward the center of the sarcomere during contraction. They facilitate this movement by using energy derived from ATP to generate a conformational change known as the power stroke. Actin and myosin both exist in a polarized state, with plus (+) and minus (-) ends, indicating the directionality of movement. Type II myosin motors pull actin filaments towards the minus end, which in the case of muscle cells, is toward the M line of the sarcomere, effectively shortening it and resulting in muscle contraction.