Patent ID: 7279317

Claim:
A method of identifying an agent for modulating COP9 Signalsome (CSN) isopeptidase activity comprising: contacting a CSN polypeptide having the amino acid sequence of SEQ ID NO:84 or 85 in the presence of a modifier protein and a target protein, wherein the CSN polypeptide has isopeptidase activity and deconjugates the modifier protein from the target protein under conditions suitable for CSN isopeptidase activity, and wherein the conditions include adenosine tri-phosphate (ATP); and determining the CSN isopeptidase activity by measuring cleavage of the modifier protein from the target protein in the presence or absence of the test agent, wherein a difference in the isopeptidase activity in the presence versus the absence of the agent is indicative of an agent that affects the isopeptidase activity of the CSN polypeptide, and wherein the target protein has ubiquitin ligase activity and wherein the modifier protein is a ubiquitin or a ubiquitin-like modifier protein.