FIG. 4.

Indirect immunofluorescence to detect intracellular or cell surface G proteins. HeLa cells were infected with vTF7-3 and transfected with the indicated mutants. After 6 h, cells were fixed and stained with rabbit polyclonal anti-VSV serum and then with a Texas red-conjugated anti-rabbit secondary antibody to detect surface G expression. The samples were then permeabilized and incubated with guinea pig anti-VSV G serum and then with a FITC-conjugated anti-guinea pig secondary antibody to show internal G expression. Cells were visualized by indirect immunofluorescence with a Nikon Microphot FX microscope and photographed with a SPOT digital camera.