USE OF GPI-ANCHORED PROTEINS TO STUDY BIOMOLECULAR INTERACTIONS BY SURFACE-PLASMON RESONANCE

Surface plasmon resonance is a powerful tool to examine the kinetics o f cell surface receptor-ligand interactions and requires only small am ounts of protein, For these studies, one component is required in high ly purified form to be coupled to the biosensor surface, The second co mponent does not need to be purified, The human high affinity receptor for immunoglobulin G, Fc gamma RI, presents a problem as the receptor itself cannot readily be produced in large amounts for purification a nd, as there are eight potential ligands for the receptor (human IgG1- 4 and mouse IgG1, 2a, 2b and 3), it is difficult to immobilise the lig and, Using a previously established method for generating GPI-anchored proteins, me have produced and captured a soluble version of Fc gamma RI and shown that it retains its affinity for human IgG1 and specific ity for the different IgG subclasses, In addition, we also produced an d captured a GPI-anchored version of the cell adhesion molecule CD2. T his system circumvents the need for extensive receptor purification an d is very rapid as solubilised receptors can be transferred from the c ell surface to the sensor chip in 2 h, This system mag be generally ap plicable for biosensor studies to other type I membrane proteins, and/ or naturally occurring GPI-anchored proteins, especially where the int eraction between a ligand and a panel of variant receptors is to be st udied. (C) 1998 Federation of European Biochemical Societies.