Tropomyosin is a protein found in muscle cells that plays a crucial role in muscle contraction. It binds to actin, another protein that forms the thin filaments of muscle fibers. Tropomyosin helps regulate the interaction between actin and myosin, the protein responsible for muscle contraction, by blocking or exposing binding sites on actin. In addition to its role in muscle tissue, tropomyosin is also present in non-muscle cells, where it contributes to various cellular functions, including maintaining cell shape and facilitating movement. Its structure allows it to stabilize actin filaments, ensuring proper cellular function and integrity.