Thursday, February 28th, 2013
3:00pm - 4:00pm, in McCormack 2-116

John Fricks

Penn State University

Multiple Scales in Molecular Motor Models

Abstract: Molecular motors, such as kinesin and dynein, carry cargo through a cell along a microtubule network. The heads of these motors step along a microtubule and are on the order of nanometers, while the cargo size and the distance traveled can be on the order of hundreds of nanometers. Stochastic models of motors that describe and bridge these spatial scales will be discussed along with how data can be incorporated into these models at the various scales. A stochastic model for variable-length stepping of kinesins engineered with extended neck linkers was developed. This requires consideration of the separation in microtubule binding sites between the heads of the motor at the beginning of a step. The separation is a stationary process and can be included in the calculation of standard experimental quantities though a semi-Markov framework by using weak convergence results from stochastic processes theory. In order to better understand how both single and multiple motors can influence the motion of a cargo, a stochastic model for microtubule-motor-cargo dynamics is presented that emphasizes the spatial configuration and the resultant distribution of forces generated on and by the cargo. Using stochastic averaging, a simplified model parameterized with in vitro data can be studied to gain insight into the in vivo behavior of the motor-cargo system.