Patent ID: 7824850

Claim:
An in vitro method of detecting a protease activity in a cell, comprising; a) providing a cell comprising, i) at least one destabilization domain, wherein said destabilization domain is non-cleavable by α-NH-ubiquitin protein endoproteases, ii) a reporter moiety, and iii) a linker moiety that operatively couples said destabilization domain to said reporter moiety, wherein said linker moiety comprises a protease cleavage site for said protease activity and cleavage of said linker moiety by said protease activity decreases the coupling of said destabilization domain to said reporter moiety thereby increasing the stability of said reporter moiety, and wherein said linker moiety is non-cleavable by said α-NH-ubiquitin protein endoproteases; and b) detecting said reporter moiety, or a product of said reporter moiety, thereby detecting the protease activity in the cell.