Knowra Actin filament Actin filament An actin filament is a thin, polarized polymer assembled from actin protein subunits. Its rapid assembly and disassembly help cells maintain shape, move, and divide.
Actin polymerization : The addition of actin monomers to a growing filament, driven by nucleotide-dependent subunit interactions. Polymerization extends filaments, especially at their fast-growing barbed ends.
Actin : A highly conserved protein that polymerizes into filaments and participates in cell structure and movement. Actin monomers are the repeating subunits of the filament.
Lamellipodium : A broad, sheet-like protrusion at a cell’s leading edge, supported by a branched actin network. Branched filaments push the membrane forward during crawling.
Microtubule : A hollow cytoskeletal polymer made from tubulin, used in intracellular transport, cell organization, and chromosome separation. Microtubules are stiffer and wider, with different motors and cellular roles.
Treadmilling : A steady state in which subunits add at one end of a polymer and leave at the other. Actin filaments can maintain length while subunits flow through them.
F-actin : Filamentous actin: the polymeric form of actin assembled from globular actin subunits. This name emphasizes the polymer rather than its soluble subunits.
Filopodium : A narrow, finger-like cell protrusion supported by parallel bundles of actin filaments. Bundled filaments extend these protrusions for sensing and movement.
Intermediate filament : A rope-like cytoskeletal polymer that provides mechanical resilience and lacks the polarity of actin filaments. Intermediate filaments resist stress but do not use actin-like polarized turnover.
Arp2/3 complex : A protein complex that nucleates branched actin filaments from existing filaments. It creates branched networks that push against the cell membrane.
G-actin : Globular actin, the soluble monomeric form that can assemble into actin filaments. G-actin supplies the subunits incorporated during filament growth.
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