Fig. 4.
Steady-state surface levels of protein confirm the importance of the predicted beta-hairpin. HeLa cells expressing VSV-G, G-E, G-EPA, G-EAla4, and G-EAla6 were surface biotinylated using a membrane-impermeant biotin reagent at 24 h posttransfection. Biotinylated proteins were collected from lysate using streptavidin agarose resin, washed, and eluted in sample buffer. The supernatant (10%) was collected to assess nonbiotinylated protein. After SDS-PAGE, proteins were detected with Western blotting with anti-VSV-G. S, surface protein; I, internal protein. Quantification of results from at least four independent experiments ± standard errors of the means are shown.