Figure 4
From: Mouse Antibody of IgM Class is Prone to Non-Enzymatic Cleavage between CH1 and CH2 Domains
Factors affecting IgM cleavage. Samples were analyzed using western blotting with anti-mouse IgMκ antibody. (a) Serum-induced IgM cleavage in the presence of protease inhibitors. Presented result is an example of many experiments, in which also other inhibitors, all listed in Methods section, were used. None of the single inhibitors prevented IgM trimming. (b) Serum-induced IgM cleavage at different pH. Standard sample – medium without additional buffer. (c and d) IgM cleavage induced by serum-free medium collected from Hep G2 cell culture. The medium was concentrated by ultrafiltration with 3 kDa cut-off. Cibacron Blue resin removes a factor cleaving IgM from the medium (d). The image in panel c combines data extracted from one blot presented in full in Supplementary Figure S2. (e) IgM cleavage induced by various proteins. IgM was incubated with a hundredfold excess of the indicated proteins. Samples were analyzed in duplicates or triplicates. (f) IgM stability in the presence of protamine. Representatives of ten (a), two (b,e,f), or four (c,d) independent experiments are shown.
