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A protein that forms the microfilaments of the eukaryotic cytoskeleton and plays an important role in cell movement, shape, and internal organization. In muscle cells, it functions with myosin to produce contraction.

[Latin āctus, motion; see act + -in.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Biochemistry) a protein that participates in many kinds of cell movement, including muscle contraction, during which it interacts with filaments of a second protein, myosin
[C20: from act + -in]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(ˈæk tən)

a protein that functions in muscular contraction by combining with myosin. Compare actomyosin.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.actin - one of the proteins into which actomyosin can be split; can exist in either a globular or a fibrous form
actomyosin - a protein complex in muscle fibers; composed of myosin and actin; shortens when stimulated and causes muscle contractions
simple protein - a protein that yields only amino acids when hydrolyzed
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
The study published in the Proceedings of the National Academy of Sciences (PNAS) gives the first clear details of how the binding sites of CaMKII act to align actin filaments into long, rigid bundles.
Ordinarily, as filaments of the myosin protein absorb energy, they bind to filaments of the protein actin and bend back upon themselves, pulling on the actin filaments and contracting the muscle.
FLNC belongs to the filamin superfamily and cross-links actin filaments to form a network, anchoring membrane protein to the cytoskeleton.
Previous studies have reported that CAPZB is an essential element of the actin cytoskeleton whereby it binds to the barbed ends of actin filaments and regulates their polymerization [16].
The transformation of the chemical energy released during the conformational change (stroke) into mechanical energy is brought about by the binding of CBs to actin filaments, which couples the stroking to shortening through sliding actin filaments.
Cofilin-1 (CFL1) is an actinbinding protein that is essential for the depolymerization of actin filaments (8).
Myosin II is an adenosine triphosphate (ATP)dependent protein that generates force and movement along the actin filaments. The "swinging lever-arm" hypothesis of muscle contraction purposes that nucleotide-dependent small movements of the ATPase catalytic site are amplified by the rotation of the myosin molecule "neck", and it is accepted as the general mechanism by which the sarcomere shortening occurs (Shiroguchi et al., 2011).
To visualize actin filaments, after the secondary antibody incubation, the zygotes were treated with a 200-fold dilution of rhodamine phalloidin (R415; Molecular Probes) by DW for 2 h at room temperature and then rinsed in rinse solution three times.
In the region around the nucleus (5< x <10 pm and 22< x < 30 [micro]m), there exists actin filaments network which plays a key role in cellular mechanical stability, and therefore we observe increase of elastic modulus in this area.
Considering that actin filaments are assembled by noncovalent interactions, this provides a higher potential of exchange between the monomeric and the filamentous states.
Maruyama, "Human T cell L-plastin bundles actin filaments in a calcium dependent manner," Journal of Biochemistry, vol.