Question

Which of the following proteins are not found in muscle fibres?

(a) keratin

(b) actin

(c) troponin

(d) tropomyosin

The question was asked in final exam.

This interesting question is from Cell Motility topic in division Cytoskeleton and Cell Motility of Cell Biology

Answer 1

The correct answer is:

(a) keratin

Explanation:

Keratin is a structural protein found primarily in epithelial cells, such as those in skin, hair, and nails. It is not involved in muscle contraction.

The other proteins listed are all involved in muscle function:

• Actin is a key component of the thin filaments in muscle fibers and is essential for muscle contraction.
• Troponin is a regulatory protein complex that, along with tropomyosin, controls the interaction between actin and myosin in muscle contraction.
• Tropomyosin is another regulatory protein that binds along the actin filaments, blocking the myosin binding sites in relaxed muscle.