The other two protein molecules that form the thin filaments are called troponin and tropomyosin. The molecules of tropomyosin cover the myosin-binding sites on the actin molecules when the muscle fibres are relaxed.
Similarly, what are thick and thin filaments composed of?
Myofibrils are small, cylindrical structures located within the sarcoplasm of a skeletal muscle. Myofibrils consist of bundles of thick and thin protein filaments, generally called myofilaments. Thick filaments are composed of myosin only. The proteins in thin filaments are actin, tropomyosin, and troponin.
What is the protein that composes the thick filaments?
Each myosin molecule is shaped like a golf club, with the head of the golf club pointed out from the surface of the thick filament. This structure will form the cross bridge that binds to the thin filament. Actin is the main protein of the thin filament. A second protein, called troponin, is found at intervals.
What is in a thin filament?
The thin filaments are approximately 7-9 nm in diameter. They are attached to the z discs of the striated muscle. Each thin filament is made up of three proteins: (1) actin, (2) troponin, and (3) tropomyosin. Actin though is the main protein component of the thin filament.