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Cell surface (cortical) actin remodeling is a cyclic (9-step) process where each step is directly responsive to a cell signaling mechanism. Over the course of the cycle, actin begins as a monomer, elongates into a polymer with the help of attached actin-binding-proteins, and disassembles back into a monomer so the remodeling cycle may commence again.
Many actin-related molecules create a free barbed end for polymerization by uncapping or severing pre-existing filaments and using these as actin nucleation cores. However, the Arp2/3 complex stimulates actin polymerization by creating a new nucleation core. Actin nucleation is an initial step in the formation of an actin filament.
The nucleation of new actin filaments – the rate-limiting step in actin polymerization – is aided by actin-nucleating proteins such as formins (like formin-2) and the Arp2/3 complex. [118] Formins help to nucleate long actin filaments. They bind two free actin-ATP molecules, bringing them together.
Actin plays a role in the formation of new spines as well as stabilizing spine volume increase. [1] The changes that actin brings about lead to the formation of new synapses as well as increased cell communication. Actin remodeling consists of the dynamic changes in actin polymerization that underlie the morphological changes at the neural synapse.
(Single white dots represent monomers and black chains represent oligomers and polymers) [1] Comparison of molecular weight vs conversion plot between step-growth and living chain-growth polymerization. In polymer chemistry, step-growth polymerization refers to a type of polymerization mechanism in which bi-functional or multifunctional ...
Cytoskeletal drugs are small molecules that interact with actin or tubulin.These drugs can act on the cytoskeletal components within a cell in three main ways. Some cytoskeletal drugs stabilize a component of the cytoskeleton, such as taxol, which stabilizes microtubules, or Phalloidin, which stabilizes actin filaments.
The unfavorable kinetics of actin oligomer production prevent spontaneous actin polymerization. [2] Once an actin nucleus has been created, the connection of the monomers happens swiftly, with the plus end developing considerably more quickly than the minus end. [2] Actin's ATPase activity sharply rises after insertion into the filament. [2]
In chain-growth (or chain) polymerization, the only chain-extension reaction step is the addition of a monomer to a growing chain with an active center such as a free radical, cation, or anion. Once the growth of a chain is initiated by formation of an active center, chain propagation is usually rapid by addition of a sequence of monomers.