Fig. 5. Cell-surface expression of flag-p32 species. (a) Staining of non-permeabilised cells demonstrates cell-surface expression of flag-p32 constructs. COS-1 cells transfected with p32-myc or flag-p32-myc were fixed in 4% paraformaldehyde and analysed with anti-myc antibody. (b,c) Cell-surface biotinylation of p32 expression constructs. COS-1 cells were transfected with flag-p32 (lanes 1), flag-p32-myc (lanes 2) and p32-myc (lanes 3) and 40 hours later labelled with membrane-impermeable Sulfo-NHS-LC-biotin. (b) Total extracts (5x10⁴ cells per lane). (c) Streptavidin-bound, cell-surface expressed, extract (5x10⁵ cells per lane). Proteins were detected by western blot using the indicated antibodies. * indicates proteolytically cleaved p32.