Abstract:
:A one-dimensional kinetic Ising model is developed to describe the binding of myosin subfragment 1 (SF-1) to regulated actin. The model allows for cooperative interactions between individual actin sites with bound SF-1 ligands rather than assuming that groups of actin monomer sites change their state in a cooperative fashion. With the triplet closure approximation, the model yields a set of 16 independent differential (master) equations which may be solved numerically to yield the extent of binding as a function of time. The predictions of the model are compared with experiments on the transient binding of SF-1 to regulated actin in the presence of Ca2+ and in the absence of Ca2+ with varying amounts of SF-1 prebound to the actin filament and on the equilibrium binding of SF-1 X ADP to regulated actin in the absence of Ca2+. In all cases, the calculations fit the data to within the experimental errors. In the case of SF-1 X ADP, the results suggest that a repulsive interaction exists between adjacently bound SF-1 at the ends of two neighboring seven-site actin units.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Balazs AC,Epstein IRdoi
10.1016/S0006-3495(83)84286-6subject
Has Abstractpub_date
1983-11-01 00:00:00pages
145-51issue
2eissn
0006-3495issn
1542-0086pii
S0006-3495(83)84286-6journal_volume
44pub_type
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