Figure 2.

The synthesis of high amounts of IgA/G is not imposing stress onto the secretory pathway of mesophyll cells. Protoplasts from wild-type (SR1) or transgenic tobacco plants expressing IgA/G were transiently transfected with plasmids encoding phaseolin Δ418 (A) or T343F (B). Cells were labeled for 1 h with ³⁵S-methionine and -cysteine and chased for the indicated periods of time. Total cell homogenates or incubation media were immunoprecipitated with anti-phaseolin antiserum and polypeptides were visualized by SDS-PAGE and fluorography. The arrowhead indicates the position of intact phaseolin. The vertical bar in B indicates the position of vacuolar fragmentation products of phaseolin. Numbers at left indicate molecular mass markers in kilodaltons.