actin

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Related to actin filament: Intermediate filament, myosin filament

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 ?
This size coincides with the interval between neighboring actin monomers subunits on one of two strands in an actin filament.
Molecular mechanisms controlling actin filament dynamics in nonmuscle cells.
Magnetization of an ATP-activated actin filament manifests that naturalized dynamics accessible in first- and second-person descriptions eventually comes to yield what look like boundary conditions that can be seen as a robust consequence of the interplay between the conflicting microdynamic contexts.
Additionally, living isolated pharynxes were treated with dihydrocytochalasin B, a compound known to disrupt actin filaments.
2+] by comparing the mechanical movement of actin filaments for Physarum and scallop myosin.
The regulative cascades of actin filament regulators are only partially known.
2+]-dependent movement of troponin and tropomyosin on actin filament, (ii) the interaction site(s) with myosin, and lastly (iii) the structure of the tropomyosin junction, of which the formation is essential to bind to actin filaments.
The neck of myosin molecule plays a vital role in cellular movement and acts as a lever arm which amplifies the small conformational change developed in the head by ATP hydrolysis and relatively advances the actin filament by one step.
The enzyme puts out a very large torque, considering that the actin filament is more than 100 times the length of the enzyme itself, Yoshida says.
The actomere--usually a short actin filament bundle--functions as a nucleating site that seeds the polymerization of actin filaments.
Calcium regulation of actin filament capping and monomer binding by macrophage capping protein.
This is consistent with the importance of anaphase entry for somatic furrowing, as evident in early work on echinoderm zygotes whose asters had been removed or disrupted (Cornman and Comman, 1951; Swann and Mitchison, 1953; Mitchison, 1953; Scott, 1960), and in later studies on the appearance of actin filament bundles in the cortex (Mabuchi, 1994).