Isolation of isoform-specific binding proteins (Affimers) by phage display using negative selection

Some 30 years after its discovery, phage display remains one of the most widely used methods of in vitro selection. Initially developed to revolutionize the generation of therapeutic antibodies, phage display is now the first choice for screening artificial binding proteins. Artificial binding proteins can be used as reagents to study protein-protein interactions, target posttranslational modifications, and distinguish between homologous proteins. They can also be used as research and affinity reagents, for diagnostic purposes, and as therapeutics. However, the ability to identify isoform-specific reagents remains highly challenging. We describe an adapted phage display protocol using an artificial binding protein (Affimer) for the selection of isoform-selective binding proteins.