Question

ATPase enzyme needed for muscle contraction is located in
(a) Actinin
(b) Troponin
(c) Myosin
(d) Actin

Answer 1

Hint: It is a common protein found in the muscles which are responsible for making the muscle contract and relax. It is an outsized, asymmetric molecule, and has one long tail also as two globular heads. If dissociated, it'll dissociate into six polypeptide chains. Two of them are heavy chains that are wrapped around each other to form a double helical structure, and the other four are light chains.

Complete answer:
During muscle contraction, myosin cross-bridges the heads. It contains an actin-binding protein as well as an ATPase, which is activated by ${ Ca }^{ 2+ }$ and ${ Mg }^{ 2+ }$ ions.

Additional Information: Myosins are an outsized superfamily of engine proteins that move along actin fibers while hydrolyzing ATP to kinds of energy which will be utilized for a spread of capacities such as muscle movement and contraction. About 20 classes of myosin are distinguished from the idea of the sequence of amino acids in their ATP-hydrolyzing motor domains. The different classes of myosin also differ in the structure of their tail domains. Tail domains have various functions in several myosin classes, including dimerization and other protein-protein interactions.
One principal characteristic of myosin is its capacity to tie explicitly with actin. When myosin and actin are combined together, that creates the muscle-producing force.
So the correct answer is ‘Myosin’.

Note: Myosin has groups of proteins that divide the motor proteins. The motor proteins are including actin filaments that hydrolyze ATP. There are 20 different types of Myosin that are already distinguished by amino acid sequences. All 20 types of Myosin have different structures followed by the tail domain. Each class has the characteristic of dimerization and protein interactions. However, there are known classes in Myosin. Myosin I, Myosin II, Myosin V, and VI.