Physics Colloquium
Friday, January 28th, 2005, 4:00 P.M.

Andrew Pomerance

University of Maryland

Cell Motility: Actin Up

Cells are very dynamic systems that orchestrate the activities of hundreds or even thousands of proteins in order to move around in their environment. An integral part of this motility, naturally, is the ability to produce forces. It has been known by biologists for decades that cells control the polymerization of actin, a near-ubiquitous biopolymer, in order to produce forces. However, only recently have the mechanisms of force-production been elucidated. In this talk, I will discuss two ways in which actinpolymerization can produce forces: in a bacterium, L. monocytogenes, the host cells machinery is hijacked by the bacterium to propel itself; in vitro, we have found that a gradient in polymerization fraction gives rise to forces that extrude impurities. In particular, I will describe contributions of physicists to characterizing and understanding these complex systems.