Which structural protein of the sarcomere spans from the Z line to the M line and is responsible for passive elastic recoil and centring of the thick filament?
- A Titin ✓
- B Alpha-actinin
- C Nebulin
- D Myomesin
Correct answer: A. Titin
Explanation
Titin is the largest known protein and runs from the Z disc to the M line, acting as a molecular spring that provides passive tension at rest and holds the thick filament centred between two Z lines. Nebulin runs along the thin filament and regulates its length, alpha-actinin anchors actin at the Z line, and myomesin links thick filaments at the M line. Their localisations make each one identifiable and eliminate them.
Reference: Guyton and Hall Textbook of Medical Physiology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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