Thin filaments

Definition

Thin filaments are protein structures found in muscle fibers essential for muscle contraction. They primarily consist of actin, along with regulatory proteins troponin and tropomyosin.

5 Must Know Facts For Your Next Test

1. Thin filaments are about 7-8 nanometers in diameter.
2. Actin molecules in thin filaments form a helical structure.
3. Troponin binds to calcium ions, causing conformational changes that move tropomyosin away from myosin-binding sites on actin.
4. During muscle contraction, thin filaments slide past thick filaments (myosin) to shorten the sarcomere.
5. Thin filaments are anchored at the Z-line of the sarcomere.

Review Questions

Related terms

Thick Filament: Composed mainly of myosin, these structures interact with thin filaments during muscle contraction

Sarcomere: The basic contractile unit of striated muscle fibers, defined by Z-lines and containing both thin and thick filaments

Tropomyosin:

A regulatory protein that blocks myosin-binding sites on actin molecules when a muscle is relaxed