Parking problem and negative cooperativity of binding of myosin subfragment 1 to F-actin
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Updated: May 19, 2026

Actin Co-Sedimentation Assay; for the Analysis of Protein Binding to F-Actin
Published on: March 28, 2008
Yana K Reshetnyak1, Cynthia N Prudence, James Segala
1Physics Department, University of Rhode Island, 2 Lippitt Rd., Kingston, RI 02881, USA.
Abstract:
Previously we provided evidence that myosin subfragment 1 (S1) can bind either one (state 1) or two actin monomers (state 2) in solution and in muscle fiber. Here we present results of the kinetics study of binding of S1 to F-actin labeled with fluorescent dye pyrene. A transition from state 1 to state 2 depends on probability that the second actin is free, which is high when molar ratio of S1/actin (R) is less than 0.5, and it decreases dramatically when R>2.0 due to the parking problem. The kinetics data obtained at different molar ratios were well fitted by two binding states model. The sequential binding of myosin head initially with one actin monomer and then with the second actin monomer in F-actin can play a key role in force generation by actin-myosin and their directed movement.
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