Fig. 6. In vitro filament bundling. (A-C) Fluorescently labelled actin filaments were incubated with IRTKS IMD (A), with IRTKS IMD-Ct (B) or with no additions (C) then imaged using a fluorescence microscope. IMD induces long bundles, whereas IMD-Ct induces short, clustered bundles. Bars, 20 µm. (D,E) 5 µM F-actin was incubated with the indicated concentrations of IRTKS IMD or IMD + Ct and then centrifuged at 10 000 g. Pellets and supernatants were analysed by SDS-PAGE after staining with Coomassie Blue. There is an IMD concentration-dependent increase in pelleting of actin, indicating filament bundling.