Western blot analysis of exogenous human IgG
κ incubated with wild type N. tabacum leaf extract with or without protease inhibitor cocktail. Leaf discs from wild type N. tabacum plants were extracted in either PBS (-) or PBS supplemented with a protease inhibitor cocktail (+) and exogenous human IgG1κ (1.8 ng/lane) was added. The mixtures were incubated at room temperature for the indicated times and proteins separated by 6% SDS-PAGE under non-reducing conditions. The proteins were blotted onto nitrocellulose and probed with anti-human γ1 (Fc region specific) antiserum (Panel A) or anti-human κ antiserum (Panel B). The control (PC), is a human IgG1κ (1.8 ng/lane). The asterisk indicates the fully assembled 2G12 antibody; lower case letters (a, b and c) indicate antibody fragments.