Fig. 6.

Stability of p24 proteins of the beta subfamily. Tobacco mesophyll protoplasts were electroporated in the absence (–DNA) or the presence of 30 μg of plasmid DNAs corresponding to GFP–p24β2 (upper panel) or GFP–p24β3 (middle panel), in the absence (Control) or the presence of MG-132 or E-64. At 24h post-electroporation, protoplasts were washed and homogenized to obtain a post-nuclear supernatant, which was then centrifuged to obtain a total membrane fraction. Membranes were extracted in Laemmli sample buffer and analysed by SDS–PAGE (12% acrylamide) and western blot analysis with antibodies against Ct-p24β2 or GFP (to detect p24β3). A 30 μg aliquot of protein was loaded for each of the extracts. Western blotting with an antibody against the plasma membrane (PM) ATPase was used as a loading control (lower panel).