Patent ID: 7109293

Claim:
A chimeric protein comprising at least one signal protein that has a trafficking signal targeting to a subcellular organelle and at least one proteolytic cleavage site for a protease, which is constructed such that (a) the trafficking signals of all the signal proteins are inactivated by linking the proteolytic site or a signal masking protein through the proteolytic site to the N- or C-terminus of the signal proteins, and thus the chimeric protein is present in cytosol; (b) the trafficking signal of at least one signal protein is activated when the proteolytic cleavage site is cleaved by the protease, and as a result at least one fragment protein that includes the activated signal protein is transported to a subcellular organelle; and (c) the chimeric protein is labeled with at least one detectable amino acid sequence and the position and intensity distribution of the detectable amino acid sequence signal in the cell is altered depending on the cleavage by the protease.