Ligand Selection by Rescue of Phage Infectivity

Improved methods for the identification of physiologically important protein-protein interactions ademand. We Have devised a novel system which allows the selection of protein or peptide ligands of afrom complex mixtures by virtue of their ability to facilitate the replication of their own genes. Afilamentous phage display on non-infectious phage. The protein of interest, or 'bait' protein, is exinfectivity-conferring fragment of the minor phage coat protein, which is secreted into the periplasexpression of the cDNA library and the 'bait' protein construct in the same cell will result in thephage when and only when the cDNA translation product has significant affinity for the 'bait' proteiwith their genes encoded in the phage, can then be recovered by simple plaque assay, or they can begrowth in suspension. This method has important advantages over comparable methods such as the two-hshould be useful for extracellular interactions and should produce lower false positive backgrounds.