ANATOMY

Detailed explanation-1: -The thick filaments of muscle consist of several hundred myosin molecules, associated in a parallel staggered array by interactions between their tails (Figure 11.23). The globular heads of myosin bind actin, forming cross-bridges between the thick and thin filaments.

Detailed explanation-2: -The thick filament consists largely of myosin. Six proteins make up myosin: two heavy chains whose tails intertwine to form a supercoil and whose heads contain actin binding sites and a catalytic site for ATP hydrolysis.

Detailed explanation-3: -The thick filaments are composed of myosin with the globular heads forming cross-bridges with thin filaments. Myosin-binding proteins, including MyBP-C, are associated with the thick filaments. The giant protein titin extend the length of an entire half sarcomere.

Detailed explanation-4: -Myofibrils Are Composed of Actin and Myosin Filaments Each myofibril (Figure 6-1D andE) is composed of about 1500 adjacentmyosin filaments and 3000actin filaments, which are large polymerized protein molecules that are responsible for the muscle contraction.

Detailed explanation-5: -In striated muscle cells, myosin forms the backbone of the thick filaments, which are anchored within the M-band and extend bidirectionally toward the two opposite ends of the sarcomere (171, 247).