Negative staining and electron microscopy reveal actin bundling by
recombinant fascin 2b fusion protein. Micrographs display filamentous
actin in the absence of MBP-fascin 2b (A) and in the
presence of MBP-fascin 2b (B); bundled filaments are
observed in B. Scale bars are 100 nm. An immunoblot
(C, top), from a cosedimentation experiment, shows the
progressive depletion of MBP-fascin 2b from supernatants incubated with
increasing concentrations of actin; molar concentration (C,
middle) of actin for each lane is displayed. Image of a gel
(C, bottom), after SDS-PAGE and exposure to SYPRO Ruby
protein gel stain, shows the actin found in pellets from a
cosedimentation experiment. Plotted are the means of specific
equilibrium-binding measurements of MBP-fascin 2b to filamentous actin
(D). Each point is a mean ± SEM (number of
experiments, N = 4) or an average of two
experiments (no error bars).