actinecytoskelet

The actinecytoskelet, commonly called the actin cytoskeleton, is a dynamic network of actin filaments and associated proteins that provides structural support, shapes the cell, and generates forces for movement and division. In eukaryotic cells, actin monomers (G-actin) polymerize into filamentous actin (F-actin), forming a flexible framework that interacts with other cytoskeletal systems to coordinate intracellular organization and signaling.

The organization and turnover of actin filaments are tightly regulated. Nucleation is driven by factors such as the Arp2/3 complex and formins, while actin-binding proteins regulate filament growth, branching, severing, and stability. Profilin, thymosin, cofilin, capping proteins, and tropomyosin modulate polymerization dynamics and filament integrity. Filament structures include lamellipodia and filopodia at the leading edge of migrating cells, as well as stress fibers connected to focal adhesions. During cell division, actin forms a contractile ring that helps physically separate daughter cells.

Functions of the actinecytoskelet include maintaining cell shape, enabling movement and adhesion, and organizing intracellular trafficking and organelle positioning. It participates in endocytosis and exocytosis and contributes to mechanotransduction, translating mechanical forces into biochemical signals. In muscle cells, actin filaments interact with myosin to drive contraction within sarcomeres, a specialized use of the actin cytoskeleton in muscle tissue.

Dysregulation of actin dynamics is associated with developmental abnormalities, cancer progression, and immune dysfunction. Research tools include fluorescent labeling of F-actin (for example, phalloidin staining), live-cell imaging of actin reporters, and drugs that disrupt polymerization (such as cytochalasin D or latrunculin).