Fig. 1.
Electron micrographs of negatively stained pure F-actin (a), and F-actin after incubation with coronin-1A (b).The space bar is 500 Å. G-actin (10 μM) was polymerized in 10mM Tris-HCl buffer (pH 7.7), 0.1 mM ATP, 40 mM KCl, 2mM MgCl2 for ∼ 2 hr. Then F-actin (1.5 μM) was incubated with coronin 1A (4-5 μM) for 4-10 min before application to carbon coated glow discharged EM grids The grids were stained with 1% uranyl acetate (w/v) and imaged in a Tecnai 12 electron microscope (80 keV, × 30,000 magnification). Images were recorded on film, and negatives were scanned with a Nikon Coolscan 8000 densitometer at a raster of 4.2 Å/pixel.