Patent ID: 7435546

Claim:
A method for identifying a polypeptide sequence capable of translocating into a cell nucleus in response to induction by an extracellular stimulus, said method comprising: (a) providing a population of cells comprising a first reporter gene encoding a first reporter polypeptide, said first reporter gene operably linked to a transcriptional regulatory sequence comprising a DNA binding site for a DNA-binding domain; (b) introducing into the population of cells an expression vector comprising a regulatory sequence operably linked to a nucleotide sequence encoding a fusion protein, said fusion protein comprising a polypeptide sequence, said DNA-binding (DB) domain, and a transcriptional activation (TA) domain, wherein said DB and TA domains do not confer an ability to translocate into a cell nucleus, and wherein binding of said DB domain of said fusion protein to said transcriptional regulatory sequence operably linked to said first reporter gene activates transcription of said first reporter gene; (c) dividing the population of cells of step (b) into at least two sub-populations; (d) treating a first sub-population of cells with an extracellular stimulus, wherein said extracellular stimulus induces translocation of said fusion protein if said polypeptide sequence of said fusion protein comprises a translocatable element responsive to said extracellular stimulus, and treating a second population of cells with a control substance; and (e) assessing said first reporter gene expression in said first and second sub-populations of cells, wherein detecting an increase in said first reporter gene expression in said first sub-population of cells relative to that of said second sub-population of cells identifies the polypeptide sequence capable of translocating into the cell nucleus in response to said extracellular stimulus, wherein said first reporter gene expression is transcriptionally activated by binding of said DB domain of said fusion protein to said transcriptional regulatory sequence operatively linked to said first reporter gene following translocation of said fusion protein into the nucleus.