FIG. 7.

Purified 230-kDa trimers appear as spherical particles of 10 nm in length and 7 nm in width. Affinity- and gel filtration-purified 230-kDa complexes were analyzed by negative-contrast electron microscopy. Purified complexes in 20 mM HEPES buffer, pH 7.0, were adsorbed to carbon-coated gold grids and stained with 2% phosphor-wolfram acid. Micrographs were recorded with a Philips model CM12 electron microscope. Neither aggregates nor rosette formations of the complexes were observed.