Tropomüosiinin

Tropomüosin is a dimeric coiled-coil protein found in muscle and non-muscle cells. It is a component of the thin filament of the muscle sarcomere, where it works in conjunction with actin and tropomyosin. Tropomüosin plays a crucial role in regulating muscle contraction by controlling the interaction between actin and myosin. In its relaxed state, tropomüosin lies along the surface of the actin filament, partially blocking the myosin-binding sites. Upon stimulation, calcium ions bind to troponin, which in turn causes a conformational change in tropomüosin, shifting it away from the myosin-binding sites and allowing for muscle contraction. Beyond its role in muscle, tropomüosin is also found in various non-muscle cells, where it participates in a range of cellular processes including cell shape determination, cell migration, and intracellular transport. There are different isoforms of tropomüosin, encoded by separate genes, which exhibit tissue-specific expression and functional variations. These isoforms contribute to the diversity of cellular functions performed by tropomüosin. The precise mechanism by which tropomüosin regulates actin-myosin interactions is complex and involves intricate structural rearrangements within the thin filament.