Myofilaments

Definition

Myofilaments are the filaments of myofibrils, constructed from proteins, primarily actin and myosin. They play a crucial role in muscle contraction by sliding past each other to shorten muscle fibers.

5 Must Know Facts For Your Next Test

1. Myofilaments are classified into thick filaments (myosin) and thin filaments (actin).
2. The interaction between actin and myosin is powered by ATP hydrolysis.
3. Myofilaments are organized into repeating units called sarcomeres, the basic contractile unit of muscle fiber.
4. Regulatory proteins troponin and tropomyosin control the interactions between actin and myosin.
5. During muscle contraction, calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from binding sites on actin.

Review Questions

Related terms

Sarcomere: The basic functional unit of striated muscle fiber responsible for contraction.

Actin:

A protein that forms thin filaments in muscle cells and interacts with myosin for muscle contraction.

Myosin: A motor protein that forms thick filaments in muscle cells and interacts with actin to produce contraction.