actin

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actin,

a protein abundantly present in many cells, especially muscle cells, that significantly contributes to the cell's structure and motility. Actin can very quickly assemble into long polymer rods called microfilaments. These microfilaments have a variety of roles—they form part of the cell's cytoskeleton, they interact with myosinmyosin
, one of the two major protein constituents responsible for contraction of muscle. In muscle cells myosin is arranged in long filaments called thick filaments that lie parallel to the microfilaments of actin.
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 to permit movement of the cell, and they pinch the cell into two during cell division. In muscle contraction, filaments of actin and myosin alternately unlink and chemically link in a sliding action. The energy for this reaction is supplied by adenosine triphosphateadenosine triphosphate
(ATP) , organic compound composed of adenine, the sugar ribose, and three phosphate groups. ATP serves as the major energy source within the cell to drive a number of biological processes such as photosynthesis, muscle contraction, and the synthesis of
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.

actin

[′ak·tən]
(biochemistry)
A muscle protein that is the chief constituent of the Z-band myofilaments of each sarcomere.
References in periodicals archive ?
Formins are large multi-domain proteins required for the assembly of straight actin filaments found in the cytokinetic contractile ring, yeast actin cables, adherens junctions between epithelial cells and filopodial protrusions (Chang et al.
5): (1) there were were fewer cells in mitosis in the MCF7 cells treated with actein at 20[micro]g/ml for 48 h, and (2) the distribution of actin filaments was altered after treatment with actein in both the MCF7 and MDA-MB-453 cells.
These filaments, which ran parallel to the cell edge, could be the enhanced actin filaments, and together with the accumulated progeny virus particles, could have caused the bulky, puffy-cell periphery.
Dihydrocytochalasin B causes depolymerization of actin filaments by capping the fast growing end of the flaments.
Using a technique to make a pattern of active myosin molecules on a surface, they showed how cargo -- they used small beads -- could be attached to actin filaments and moved from one part of the surface to another.
2+], gelsolin severs and caps polymeric actin filaments (F-actin) (21): after binding of domain G1 and partly domain G2 to the actin filament (F-actin), gelsolin rapidly severs F-actin and then remains bound to the barbed end of one of the newly formed filaments, forming a stable cap, thus inhibiting addition of further monomers.
Our preliminary work (Ding L et al) suggests that Fn-fbind the classical alpha5betal Fn receptor, alter distribution of this receptor, disrupt actin filaments and enhance MAP kinase activation.
Cells treated for 24 hr with 10-6 M FL (Figure 2B), however, contained no visible stress fibers, but rather exhibited shortened and disorganized actin filaments.
There were some fusiform dense bodies associated with these actin filaments.
Furthermore, N-WASP contains an actin depolymerization factor/cofilin homologous region, which could be used for severing actin filaments at the pointed ends and increasing the monomeric actin concentration.
The dynamic assembly/disassembly of actin filaments, in concert with other proteins, underlies many other basic cellular processes such as cell movement, cell division, and changes in cell structure.