actin filament bundle assembly

Definition

Target type: biologicalprocess

The assembly of actin filament bundles; actin filaments are on the same axis but may be oriented with the same or opposite polarities and may be packed with different levels of tightness. [GOC:ai]

Actin filament bundle assembly is a complex process that involves the coordinated interaction of multiple proteins. Actin filaments are long, thin polymers of the protein actin that are essential for a wide range of cellular processes, including cell motility, cell division, and intracellular transport. Actin filament bundles are formed when individual filaments associate with each other in a parallel arrangement. This association is mediated by a variety of actin-binding proteins, including fascin, fimbrin, and alpha-actinin.

Fascin is a protein that binds to the sides of actin filaments and promotes their bundling. Fimbrin is another protein that binds to the sides of actin filaments, but it does so in a more flexible manner than fascin. Alpha-actinin is a protein that binds to the ends of actin filaments, helping to stabilize the bundle.

The formation of actin filament bundles is regulated by a variety of factors, including the concentration of actin monomers, the activity of actin-binding proteins, and the presence of other cytoskeletal components. The process of bundle formation is thought to involve a series of steps, beginning with the nucleation of new actin filaments. Once a filament is nucleated, it can elongate by the addition of actin monomers. The filament can then interact with other filaments, mediated by actin-binding proteins, leading to the formation of a bundle.

The organization of actin filament bundles is essential for the function of many cells. For example, actin filament bundles provide the structural support for microvilli, which are finger-like projections from the cell surface that increase surface area for absorption. Actin filament bundles are also involved in the formation of stress fibers, which are contractile bundles that help to maintain cell shape.

In addition to their structural roles, actin filament bundles are also involved in cell motility. For example, actin filament bundles are essential for the formation of lamellipodia, which are sheet-like protrusions that allow cells to crawl over surfaces.

The assembly and disassembly of actin filament bundles is a highly dynamic process, and it is constantly regulated in response to changes in the cellular environment. This dynamic regulation is essential for cells to maintain their shape, move, and respond to their environment. '
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Proteins (2)

Compounds (2)