Patent ID: 8629088

Claim:
A method of identifying proteins or protein fragments which bind to a test substance comprising the following steps: (a) contacting at least one test substance with a library of protein mixtures, wherein said library comprises at least two protein mixtures, wherein each protein mixture in the library comprises at least a first fusion protein and at least a second fusion protein, wherein said first fusion protein comprises (i) a phage coat protein, (ii) a leucine zipper domain as interaction domain, and (iii) a Sec-dependent protein translocation sequence, wherein said second fusion protein comprises (iv) a protein or protein fragment, (v) a leucine zipper domain as interaction domain, and (vi) a Tat dependent protein translocation sequence, wherein the interaction domain of the first fusion protein is covalently bound to the interaction domain of the second fusion protein via cysteine residues, wherein the interaction domain of the first fusion protein is the leucine zipper domain of the cJun protein and the interaction domain of the second fusion protein is the leucine zipper domain of the cFos protein, wherein the proteins or protein fragments of the respective second fusion proteins are different from each other; and (b) measuring of the respective binding of the test substance to the different protein mixtures of the library.