Myosin Skeletal Heavy Chain Slow/MYH7 [NOQ7.5.4D]

Myosin, a 480kD protein that interacts with actin in muscle and non muscle cells, is composed of 2 identical heavy chains (about 200kD each) and 4 light chains (about 20kD each). Conventional myosin molecules consist of two major regions: tail (rod) and globular heads; they aggregate into filaments through the tail region and interact with actin and with adenosine triphosphate (ATP) through the head region. Multiple forms of myosin heavy chains exist in skeletal, smooth and cardiac muscle and in non-muscle tissues. A spectrum of skeletal muscle fiber types is found in adult skeletal muscles. The two major skeletal muscle fiber types are type I (slow-twitch) and type II (fast-twitch). Type I muscle fibers are more efficient over long periods of time. They are mainly used for postural maintenance (such has holding the head upright), or endurance exercises (like marathon running).