BIOPHYSICAL THEORY AND MODELING |
Myosin V passing over Arp2/3 junctions: branching ratio calculated from the elastic lever arm model
Andrej Vilfan 1*
1 J. Stefan Institute
* To whom correspondence should be addressed. E-mail: andrej.vilfan{at}ijs.si.
Submitted on August 27, 2007
Revised on September 21, 2007
Accepted on 11 December 2007
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Abstract |
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Myosin V is a two-headed processive motor protein that walks in a hand-over-hand fashion along actin filaments. When it encounters a filament branch, formed by the Arp2/3 complex, it can either stay on the straight mother filament, or switch to the daughter filament. We study both probabilities using the elastic lever arm model for myosin V. We calculate the shapes and bending energies of all relevant configurations in which the trail head is bound to the actin filament before Arp2/3 and the lead head is bound either to the mother or to the daughter filament. Based on the assumption that the probability for a head to bind to a certain actin subunit is proportional to the Boltzmann factor obtained from the elastic energy, we calculate the mother/daughter filament branching ratio. Our model predicts a value of 27% for the daughter and 73% for the mother filament. This result is in good agreement with recent experimental data.
Key Words:
Actin, Arp2/3 complex, Biological models, Motor proteins, Myosin V, Single-molecule experiments
