Tropomyosin is a protein that is part of the thin filament in muscle cells. It works in conjunction with troponin to regulate muscle contraction by controlling the interaction between actin and myosin. Tropomyosin helps to regulate the availability of the myosin binding sites on actin, preventing muscle contraction when the muscle is in a relaxed state. It is a long, filamentous protein that runs along the groove of the actin helix.
