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Thermodynamic origin of cooperativity in actomyosin interactions: The coupling of short-range interactions with actin bending stiffness in an Ising-like model
 

Summary: Thermodynamic origin of cooperativity in actomyosin interactions: The coupling of short-range
interactions with actin bending stiffness in an Ising-like model
Adriano M. Alencar
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02115, USA
and Department of Pathology, Medical School of the University of São Paulo, 01246­903 São Paulo, São Paulo, Brazil
James P. Butler
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02115, USA
and Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115, USA
Srboljub M. Mijailovich
Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts 02115, USA
Received 16 July 2008; revised manuscript received 16 February 2009; published 7 April 2009
We present Monte Carlo simulations for a molecular motor system found in virtually all eukaryotic cells, the
acto-myosin motor system, composed of a group of organic macromolecules. Cell motors were mapped to an
Ising-like model, where the interaction field is transmitted through a tropomyosin polymer chain. The presence
of Ca2+
induces tropomyosin to block or unblock binding sites of the myosin motor leading to its activation or
deactivation. We used the Metropolis algorithm to find the transient and the equilibrium states of the acto-
myosin system composed of solvent, actin, tropomyosin, troponin, Ca2+
, and myosin-S1 at a given tempera-
ture, including the spatial configuration of tropomyosin on the actin filament surface. Our model describes the

  

Source: Alencar, Adriano Mesquita - Departamento de Física Geral, Universidade de São Paulo

 

Collections: Physics