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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.
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actin

[′ak·tən]
(biochemistry)
A muscle protein that is the chief constituent of the Z-band myofilaments of each sarcomere.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
[Ca.sup.2+], calcium; ATP, adenosine triphosphate; ADP, adenosine di phosphate; PPi, pyrophosphate; Pi, inorganic phosphate; G-actin, Globular actin; Table 3.
droebachiensis sperm, the rod is further extended during the acrosome reaction, due to polymerization of G-actin in the periacrosomal cytoplasm.
The resulting G-actin monomers are bound by Gc-globulin, which releases gelsolin from actin.
The role of the LD should therefore be seriously considered in any future model or mechanism that attempts to describe the polymerization of G-actin into F-actin filaments.
The mode of action of T[beta]4 comprises two separate physiological processes: first, T[beta]4 binds monomeric G-actin, preventing it from forming or joining actin filaments via profilin, which, upon binding, favors the incorporation of actin into filaments [22].
T[beta]4 is known to suppress osteogenic differentiation by sequestering G-actin and preventing its polymerization [23].
G-actin binds to megakaryocyte acute leukemia (MAL; also known as MKL1/MRTF-A), a cofactor of SRF, and sequesters it from the nucleus, therefore, causing alterations in the equilibrium between actin polymerization and depolymerization perturb differentiation [33].
Recent studies also described a specific decavanadate interaction with the actin monomer, G-actin, at the ATP binding site [3, 50].