Antigen binding of an ovomucoid-specific antibody is affected by a carbohydrate chain located on the light chain variable region

We cloned the variable regions of heavy and light chain genes of an anti-ov omucoid monoclonal antibody (MAb-OM21) produced by the mouse hybridoma cell line OM21. DNA sequence analysis showed that the light chain of the MAb-OM 21 has only one potential N-glycosylation consensus sequence in the complem entarity determining region 2 of the light chain. To find whether carbohydr ate chains are located on the light chain, we assayed for the size of the l ight chain, after treatment with N-glycosidase, by western blotting, and al so detection of the carbohydrate chains on the light chain was done using t he lectin blot assay. A N-linked carbohydrate chain has been shown to bind to the light chain. To clarify the role of this carbohydrate chain in the l ight chain, we produced carbohydrate variant antibodies by N-deglycosylatio n using glycosidase or by expressing the antibody from different host cells . The N-deglycosylated variant antibody has greater antigen binding, and th e antibody produced from the different host cells showed a reduced antigen binding activity and acquired the ability to react to ovalbumin. These resu lts suggest that antigen binding of the ovomucoid specific antibody MAb-OM2 1 can be affected by the carbohydrate chain on the light chain variable reg ion.