Actin remodeling

The remodeling of actin filaments occurs in a cyclic pattern on cell surfaces and exists as a fundamental aspect to cellular life.

During the remodeling process, actin monomers polymerize in response to signaling cascades that stem from environmental cues.

The assembly of filamentous actin arises as a result of weak, noncovalent interactions between G-actin and appears in the arrangement of a two-stranded asymmetrical helical polymer.

[1][5] The dynamic function of actin remodeling is directly correlated to the immense variability of cell shape, structure, and behavior.

In the mechanism that involves the uncapping of the barbed-end, diffusion-regulated actin polymerization of subunits bound to actin-monomer-sequestering proteins control initiation.

Thymosin and Profilin both exist as actin-monomer-sequestering proteins that maintain the ability to limit spontaneous nucleation from occurring, thus halting the actin remodeling process and returning the cycle to its first step.

Despite the presence of active capping proteins, certain inhibitors including profilin, formins, ENA and VASP promote elongation.

Relatively small ABP's such as scruin, fimbrin, and espin function by solidifying actin filament bundles.

The dynamic nature of a cell remains directly related to the actin-filament network's ability to respond to the contractile forces that result from environmental and internal cues.

This form of weak severing does not tightly cap the "barbed ends" but does allow for the disassociation of actin monomers and thus the disassembly of F-actin.

[3] Monomer sequestration that prevents spontaneous nucleation Exists as the turnover point in the actin remodeling cycle.

The absence or inhibition of these proteins results in the cell's ability to commence the actin remodeling cycle and produce elongated F-actin.