Question

In a resting muscle fibre, troponin partially covers

• A. Ca binding sites on actin
• B. Ca binding sites on troponin
• C. actin binding site on myosin
• D. myosin binding site on actin

Answer 1

The correct option is D myosin binding site on actin

Each actin filament is made up of two F actins (polymer of G actin) that are helically wound to each other. Two filaments of a protein called tropomyosin run close to the F actins throughout its length. A protein called troponin is distributed at regular intervals on the tropomyosin. In the resting state, a subunit of troponin masks the active binding sites for myosin on the actin filaments.