MUTAGENESIS OF IMMUNOGLOBULIN-LIKE DOMAINS FROM THE EXTRACELLULAR HUMAN INTERFERON-GAMMA RECEPTOR-ALPHA CHAIN AND THEIR RECOGNITION BY NEUTRALIZING ANTIBODIES MONITORED BY SURFACE-PLASMON RESONANCE TECHNOLOGY

The extracellular portion of the human interferon-gamma receptor (IFN- gamma R) is predicted to adopt two Ig-like domains each with Ig superf amily type C2 topology. Surface plasmon resonance technology has been used here to compare the equilibrium and kinetic constants for binding reactions between these and several mutant domains, and neutralising anti-IFN-gamma R monoclonal antibodies. The biosensor measurements pro vide a sensitive method for monitoring the effects of mutations on the functional epitopes recognized by the neutralising antibodies. Thus, using recombinant native-like proteins made in E. coli, the ten N-term inal residues of the receptor were found not to be essential for domai n folding, nor for recognition by the antibodies A6, D2 and gamma R38. In a similar way, residues in the interdomain region were found to pl ay an important functional role in the epitope recognized by the antib ody gamma R99.