FIG. 6.

Density gradient and ultrastructural analysis of COS-1 cells cotransfected with plasmids that encode the poliovirus 2BC and 3A proteins. (A) Cytoplasmic membranes from cells expressing 2BC and 3A proteins were separated on a 12% stock isotonic Percoll gradient; proteins in each fraction were detected by immunoblotting using antibodies directed against poliovirus 2C, poliovirus 3A, calnexin (ER), and mtHSP70 [HSP70m(mito) mitochondria]; lightest fractions are at the left. (B) Ultrastructure of COS-1 cells transfected with 2BC- and 3A-expressing plasmids. N, nucleus. Bar = 1 μm. (C) Higher-resolution image of a section of a 2BC- and 3A-transfected cell. Bar = 0.2 μm. (D) A 2BC- and 3A-transfected cell that was immunostained with antibodies directed against the 2C protein. Secondary antibodies were coupled to 15-nm gold particles. Arrows indicate double-membraned vesicles. Bar = 0.5 μm.