Question

question 2
which of the following is part of a thin myofilament?
a sarcolemma
b atp - binding site
c calcium
d globular (g) actin
e myosin

Explanation:

• Sarcolemma: It is the cell membrane of a muscle cell, not part of a thin myofilament.
• ATP - binding site: This is on myosin (a thick myofilament protein), not on thin myofilaments.
• Calcium: It is a signaling ion that interacts with thin myofilaments (binds to troponin) but is not a structural part of the thin myofilament itself.
• Globular (G) actin: Thin myofilaments are composed of F - actin (formed by polymerized G - actin), tropomyosin, and troponin. So, G - actin is a part of the thin myofilament.
• Myosin: It is the main protein of thick myofilaments.

Answer:

D. globular (G) actin