Patent ID: 7252952

Claim:
A method comprising: a) providing a plurality of cells, each comprising recombinant nucleic acids encoding a first and a second interacting protein, wherein said first and second interacting proteins are: a ubiquitin activating agent and a ubiquitin conjugating agent, a ubiquitin conjugating agent and a ubiquitin ligating agent, or a ubiquitin ligating agent and a substrate of said ubiquitin ligating agent; b) introducing into said cells a library of fusion nucleic acids encoding intein-catalyzed cyclic peptides comprising from 5′ to 3′: i) nucleic acid encoding a C-terminal intein motif; ii) nucleic acid encoding a peptide; and iii) nucleic acid encoding an N-terminal intein motif; and c) identifying a cyclic peptide that inhibits binding of said interacting proteins.