Figure 1.

SIgA/G is secreted slowly. Protoplasts from leaves of transgenic tobacco expressing SIgA/G were pulse-labeled for 1 h with [³⁵S]Met and [³⁵S]Cys either in the presence (+) or in the absence (−) of brefeldin A (BFA) and chased for the indicated periods of time. Cells and the corresponding incubation media were homogenized, subjected to immunoprecipitation with anti-IgG antiserum, and analyzed by 15% (w/v) reducing SDS-PAGE and fluorography. Numbers at right indicate molecular mass markers in kD. H, Heavy chain; L, light chain; asterisk, un-glycosylated SC.