FIG. 5.
Effect of different conditions on the conversion of disulfide-bonded GP2b/GP4 dimers into covalently linked GP2b/GP3/GP4 trimers. (Upper panel) The culture supernatant of [35S]cysteine-labeled EAV-infected cells was split into equal fractions and incubated at 4, 39, or 39°C in the presence of 20 mM NEM for the indicated times. Alternatively, equal-size aliquots of the same culture were adjusted to different pHs and incubated for 30 min at 39°C. The samples were subsequently processed as described in the legend to Fig. 4. The numbers on the left are the molecular masses, in kilodaltons, of marker proteins analyzed in the same gel. (Lower panel) The ratio between the amounts of radiolabel incorporated into the GP2b/GP3/GP4 trimers and into the GP2b/GP4 dimers was determined by phosphorimager analysis and plotted against time.