Intermittent depolymerization of actin filaments is caused by photo-induced dimerization of actin protomers

摘要: Actin, one of the most abundant proteins within eukaryotic cells, assembles into long filaments that form intricate cytoskeletal networks and are continuously remodelled via cycles actin polymer-ization depolymerization. These driven by ATP hy-drolysis, a process also acts to destabilize as they grow older. Recently, abrupt dynamical changes during depo-lymerization single have been observed seemed imply old more stable than young ones [Kueh HY, et al. (2008) Proc Natl Acad Sci USA 105:16531-16536]. Using improved experimental setups quantitative theoretical analysis , we show these represent actual pauses in depolymerization, unexpectedly caused photo-induced formation dimers filaments. The stochastic dimerization is triggered random transitions single, fluorescently labeled protomers. Each pause represents delayed dissociation dimer, statistics molecule events can be determined optical microscopy. Unlabeled do not exhibit depolymeriza-tion, which implies that, vivo, older become destabilized hydrolysis, unless this aging effect overcompensated actin-binding proteins. latter antagonism now systematically studied for using our combined method. Furthermore, discovered here provides molecular switch, control length illumination. This could used locally "freeze" dynamics