Question

The contractile protein of skeletal muscle having ATPase activity is
A. α-Actinin
B. Troponin
C. Tropomyosin
D. Myosin

Answer 1

The skeletal muscles are responsible for the movement of the muscles and ligaments. They enable locomotion in the body. Thus they require certain proteins that could contract the muscles and eventually relax them to generate the motion.

Complete answer: These special proteins are contractile proteins that initiate sliding of the cell’s not only skeletal but also cardiac and cytoskeleton muscles.
Option A:- α-Actinin-α-Actinin is necessary for the attachment of actin filaments to the Z-lines in skeletal muscle cells and the dense bodies in smooth muscle cells. The functional protein is an antiparallel dimer, which cross-links the thin filaments in adjacent sarcomeres, and therefore coordinates contractions between sarcomeres in the horizontal axis.
Option B:-Troponin-Troponins are a group of proteins found in skeletal and heart (cardiac) muscle fibers that regulate muscular contraction. Troponin tests measure the level of cardiac-specific troponin in the blood to help detect heart injury.
Option C:- Tropomyosin -Tropomyosin (TM) is an actin-binding protein, which consists of a coiled-coil dimer and forms a polymer along the length of actin by a head-to-tail overlap along the major groove of actin.
Option D:- Myosin-Myosin is a superfamily of motor proteins best known for their roles in muscle contraction and a wide range of other motility processes in eukaryotes. They are ATP-dependent and responsible for actin-based motility.

Therefore, the correct option is "D"- Myosin.

Note: The thick filament, myosin, has a double-headed structure, with the heads positioned at opposite ends of the molecule. During muscle contraction, the heads of the myosin filaments attach to oppositely oriented thin filaments, acting, and pull them past one another.