MUSCLE PHYSIOLOGY

Detailed explanation-1: -The main component of the thick filament is myosin-II (two myosin heads); each myosin-II consists of two identical myosin heavy chains (MHC). Each MHC consists of a globular head region connected to a long coiled-coil tail region via an elastic hinge region (Figure 4).

Detailed explanation-2: -Thick myofilaments are comprised of around 300 spirally arranged protein molecules called myosin. Each myosin molecule is composed of two heavy chains and four light chains.

Detailed explanation-3: -Hence the thick myofilament from the given contractile proteins is myosin. So. the correct answer is ‘Myosin’.

Detailed explanation-4: -There are three different types of myofilaments: thick, thin, and elastic filaments. Thick filaments consist primarily of a type of myosin, a motor protein – myosin II. Each thick filament is approximately 15 nm in diameter, and each is made of several hundred molecules of myosin.

Detailed explanation-5: -A single thick filament contains >200 perfectly aligned myosin molecules assembled into highly ordered bundles in which the globular motor head domains face outward and the long rod regions face inward forming a bipolar filament (20, 176) (Fig.