# Mathematics Colloquia and Seminars

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### Simple cross-bridge mechanics models and their incorporation into an actomyosin ATPase cycle

**Mathematical Biology**

Speaker: | Steve Lehman, UC Berkeley |

Location: | 2112 MSB |

Start time: | Mon, Apr 30 2012, 3:10PM |

Cross-bridge mechanisms have replaced traditional explanations of classical phenomena. Still it is a challenge to synthesize separate mechanisms into a single model that is consistent with many phenomena. Here I formulate explicit simple cross-bridge models that simulate three phenomena: the steady-state relationship between force and shortening velocity T(V-), the steady-state relationship between force and stretch velocity T(V+), and the rate of redevelopment of force development after rapid shortening (ktr), and determine the sensitivities of their key behaviors on their few essential parameters. Each simple model has a single force-producing state and a single detached state. Using data from recent experiments that put cross-bridge states in the context of the actomyosin ATPase cycle, I identify model cross-bridge states with biochemical states, and synthesize a cross-bridge model with strain-dependent attachment and detachment rates that is consistent with a recent kinetic model of the ATPase cycle.