Question

Select the correct option for contractile proteins from the given diagram labelled as (a) and

• A. a = G - actin; b = F - actin
• B. a = Meromyosin; b = Myosin
• C. a = Tropomyosin; b = Troponin
• D. a = Troponin; b = Tropomyonin

Answer 1

Answer: (C)

a = Tropomyosin; b = Troponin

Contractile proteins of muscle are actin and myosin. Actin is the main component of thin filaments and myosin is the main component of thick filaments. The given figure is of actin filament. There is usually one troponin per 6-8 actin molecules. In this, troponin (b) is attached to the protein tropomyosin (a). It is present within the groove between actin filaments. The main function of tropomyosin is to prevent contraction during relaxed condition by blocking the attachment site for the myosin crossbridge.

Thus, the correct answer is 'a = Tropomyosin; b = Troponin.'