Protein screening methods

A method of producing a library of nucleic acid-polypeptide (X-display) complexes, comprising the steps of:

• (a) providing a library of mRNA sequences comprising a sequence element complementary to a first nucleic acid linker;
• (b) providing a first nucleic acid linker operably linked to a first high affinity ligand such that the first nucleic acid linker binds to the mRNA through complementary nucleic acid base pairing;
• (c) providing a second high affinity ligand operably linked to a peptide acceptor;
• (d) providing a ligand acceptor with at least two binding sites such that the ligand acceptor binds to the first high affinity ligand and the second high affinity ligand;
• and
• (e) allowing translation of the mRNA to occur such that the peptide acceptor binds to the translated protein, thereby forming a nucleic acid-polypeptide complex linking the mRNA to the protein.