Exploiting Fc chimaeric proteins for the identification of ligands specific for the mannose receptor

The use of chimaeric molecules bearing tags easily recognised by secondary reagents has facilitated the discovery of protein-protein and protein-carbohydrate interactions using binding assays in situ, in solution and in solid phase. In this chapter we describe our experience in the use of proteins containing selected regions of the mannose receptor fused to the Fc region of human IgG1 or murine IgG2b. Using these reagents we have discovered new and unexpected ligands for the mannose receptor. These ligands were first detected in tissue section using standard histological techniques or ligand blots of whole tissue lysates, identified using affinity chromatography and N-terminal protein sequencing and confirmed using ligand blots or solid-phase-binding assays using purified proteins. These findings have dramatically changed the way we think about this molecule.