Question

Globular protein which masks active sites on F-actin is

• A. Troponin
• B. Tropomyosin
• C. Myosin
• D. Light meromyosin
• E. Heavy meromyosin

Answer 1

The correct option is A Troponin

Troponin is a globular protein which is attached to the protein tropomyosin which lies on actin filaments in muscle tissue in the relaxed muscle. This blocks the attachment site for the myosin cross-bridge, thus preventing contraction. When the muscle cell is stimulated to contract, the calcium ions attaches to troponin, which causes it to change shape, exposing binding sites for myosin on the actin filaments. Myosin's binding to actin causes cross-bridge formation and contraction of the muscle begins. So, the correct answer is 'Troponin'.