Western blot analysis of recombinant MAb 2G12 extracted from transgenic N. tabacum in different pH-buffers. Leaf discs from MAb 2G12-expressing plants were extracted in solutions buffered to; pH 3.0, pH 4.2, pH 5.0, pH 6.2, pH 7.4, or pH 8.0. The mixtures were incubated at room temperature for 15 mins (Panel A) or 24 hrs (Panel B). Proteins were separated by SDS-PAGE under non-reducing conditions. Proteins were blotted onto nitrocellulose membranes and probed with anti-human κ antiserum. The asterisk corresponds to the fully assembled 2G12 antibody, while the lower case letters (a to j) indicate antibody fragments.