The thin filaments are stabilized by being capped by __________ at one end and CapZ at the other.
A)troponin
B)tropomodulin
C)tropomyosin
D)a polymer of all three

Question

Quizplus · Accepted Answer

The statement is referring to the capping proteins of the thin filaments in muscle sarcomeres. Tropomodulin (choice B) is known to cap the pointed end of the thin filament while CapZ caps the barbed end. Troponin (choice A) is a regulatory protein that binds to tropomyosin and plays a role in muscle contraction, but it does not cap the ends of the thin filament. Tropomyosin (choice C) is a protein that runs along the actin filament and helps regulate muscle contraction, but it does not cap the ends of the filament. Choice D is not a likely answer because it suggests a polymer of all three proteins caps the ends, which is not consistent with current knowledge of thin filament structure.

The Thin Filaments Are Stabilized by Being Capped by __________