Isolation of raft membranes from HSB-2 cells; the detection of cellular proteins. (A) Mock-infected HSB-2 cells. Bottom-loaded sucrose step gradients (fraction 1 represents the top of the gradient) were analyzed by immunoblotting. Immunoblots of proteins from each fraction (equal volume loaded) were labeled with anti-CD59 (a), -CD3zeta (b), -LAT (c), -CD46 (d) or -TfR (e) antibody for cellular proteins. GM1(f), which migrated with the dye front, was detected by reaction with HRP-coupled cholera toxin. (B) HHV-6A, strain GS-infected HSB-2 cells. HSB-2 cells were infected with GS, at 4 days later, the cells were combined with newly prepared cells, and the step was repeated. When HHV-6 infected HSB-2cells showed evidence of more than 80% infection by immunofluorescence assay (IFA), the cells were harvested for the isolation of raft fractions. The population of infection was examined by the expression of late proteins (gQ1, gQ2, gB and gL). P indicates pellet. The experiment was done three times independently, and one of three experiments was shown here. All of these blots came from the same experiment, but the exposure time of each blot was not identical.