Actin is a protein found in all eukaryotic cells, serving as a major component of the cytoskeleton. It is highly conserved and plays a crucial role in various cellular processes.

Description

Actin, also known as filamentous actin (F-actin), is a globular protein that polymerizes to form long, thin fibers called microfilaments. These microfilaments are involved in many cellular functions such as cell motility, muscle contraction, cell division, and maintenance of cell shape.

Structure

The actin monomer consists of a single polypeptide chain that folds into a compact three-dimensional structure. It features an ATP binding site, which allows actin to bind and hydrolyze ATP, providing energy for polymerization and depolymerization.

Functions

• Cytoskeletal Support: Actin filaments provide structural support to the cell and help maintain cell shape and integrity.
• Cell Motility: By assembling and disassembling actin filaments, cells are able to change their shape, migrate, and carry out various forms of movement.
• Muscle Contraction: Actin is a major component of muscle fibers and interacts with myosin to enable muscle contraction.
• Cell Division: Actin plays a crucial role in cytokinesis, the process of cell division, by forming the contractile ring that aids in the separation of daughter cells.
• Intracellular Transport: Actin participates in the movement of organelles, vesicles, and other cellular components within the cytoplasm.

Actin Binding Proteins

Actin interacts with numerous actin-binding proteins (ABPs) that regulate its polymerization, depolymerization, and organization within the cell. Some examples of ABPs include tropomyosin, profilin, cofilin, and myosin.