Biophysical Society Thematic Meeting | Riga 2026

Active and Responsive Soft Matter: From Biological to Engineered Systems

Thursday Speaker Abstracts

HOW MOLECULAR-LEVEL MOTOR FORCES ADD UP TO LARGE-SCALE STRESSES Anders E. Carlsson 1 ; 1 Washington University, St Louis, MO, USA Molecular motors such as myosins, kinesins, and dyneins generate picoNewton-scale forces on cytoskeletal filaments. These forces add up to larger-scale stresses, such as those in the actomyosin cortex, the forces that cells exert on substrates and three-dimensional environments, and the bending stresses generated by dynein-microtubule arrays in cilia and waving flagella. But the relationship between the distribution of molecular motors and the stress is not always straightforward. One would be tempted to start by adding up the magnitudes of the all the forces, but this would be wildly inaccurate. In fact, the forces exerted by any individual motor protein must cancel each other, or the protein would rapidly run away. The talk will address the relationship between the concentration of myosin motors in actin bundles and networks, and the stress. Beginning with an optimal model in which myosin motors reside at actin filament minus ends and stress propagates freely through the filaments, a formula analogous to the ideal-gas law is found that gives a proportionality between motor concentration and stress. The proportionality factor involves the length over which stress can propagate through the system without being blocked by, for example, crosslinking points.

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