actin


actin
/ak"teuhn/, n. Biochem.
a globulin that is present in muscle plasma and that in connection with myosin plays an important role in muscle contraction.
[1940-45; perh. ACT + -IN2]

* * *

One of two proteins responsible for contraction of muscle cells and the motility of other cells.

It occurs as a monomer, G-actin, a globular protein, and in living cells as a polymer, F-actin, which resembles two strings of beads twisted around each other into thin filaments. The filaments occur in regular structures, alternated and interwoven with thick filaments that contain myosin, the other major muscle protein. The thick and thin filaments slide past each other, under the control of calcium ions, resulting in contraction (shortening) and relaxation (lengthening) of the muscle cells.

* * *

      protein that is an important contributor to the contractile property of muscle and other cells. It exists in two forms: G-actin (monomeric globular actin) and F-actin (polymeric fibrous actin), the form involved in muscle contraction. In muscle, two long strands of beadlike actin molecules are twisted together to form a thin filament, bundles of which alternate and interdigitate with bundles of thick filaments formed of myosin, the most abundant protein found in muscle. Two other muscle proteins, tropomyosin and troponin, regulate the temporary fusion of actin and myosin; this fusion results in the contraction of muscle.

      Actin and myosin have been found in dozens of other (nonmuscle) cells and are believed to be responsible for the contractile properties of animal cells generally.

* * *


Universalium. 2010.

Look at other dictionaries:

  • actin- — ⇒ACTIN(O) , (ACTIN , ACTINO ), élément préf. Tiré du gr. aktis, aktinos « rayon », sert à former des subst. et qq. adj. sav. appartenant en gén. aux sc. naturelles (biol., bot., zool., except. minér.), ou, plus récemment, à la physico chim. nucl …   Encyclopédie Universelle

  • actin — actin. См. актин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Actin... — Actin... (v. gr.), strahlen …   Pierer's Universal-Lexikon

  • Actin — Actin, in fast allen Zellen vorhandenes Protein, das als globuläres A. (G. A.) und, wenn dieses zu Filamenten polymerisiert, als F. A. vorkommt. Actinfilamente heißen auch ⇒ Mikrofilamente …   Deutsch wörterbuch der biologie

  • actin — v. actino . Trimis de LauraGellner, 13.09.2007. Sursa: DN …   Dicționar Român

  • actin — [ak′tin] n. [< L actus (see ACT1) + IN1] a protein in muscles: see ACTOMYOSIN …   English World dictionary

  • actin- — [ak′tin] combining form ACTINO : used before a vowel [actinal] …   English World dictionary

  • Actin — G Actin (PDB code: 1j6z). ADP and the divalent cation are highlighted …   Wikipedia

  • Actin — G Aktin (PDB code: 1j6z) mit ADP und Kation F Aktin; Darstellung von 13 Aktin Untereinheiten (basierend auf dem …   Deutsch Wikipedia

  • Actin — Ac|tin 〈n. 11〉 = Aktin * * * Ac|tin [lat. actus = Tat, Tätigkeit, Bewegung; ↑ in (3)], das; s, e; S: Aktin: haupts. im Muskelgewebe konzentriertes Protein, das in monomerer Form als globuläres Polypeptid (G Actin aus 375 Aminos …   Universal-Lexikon


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.