Patent ID: 7052843

Claim:
An assay method for detecting the post-translational modification of a target protein by a post-translational modifier polypeptide molecule comprising: providing a first cell containing: a first plasmid having an expression unit comprising a first nucleic acid molecule encoding a DNA binding domain operably linked to a second nucleic acid molecule encoding a target protein, wherein expression of the DNA binding domain and target protein in the cell produces a DNA binding domain-target protein fusion protein; a second plasmid having an expression unit comprising a first nucleic acid molecule encoding a reporter protein operably linked to a second nucleic acid molecule encoding a DNA binding site to which the DNA binding domain of the DNA binding domain-target protein fusion protein is capable of binding, and wherein expression of the reporter protein is under control of the DNA binding site; and a third plasmid having an expression unit comprising a first nucleic acid molecule encoding a transcription activation domain operably linked to a second nucleic acid molecule encoding a known or suspected post-translational modifier polypeptide, wherein expression of the transcription activation domain and post-translational modifier polypeptide in cells produces a transcription activation domain-post-translational modifier polypeptide fusion protein; providing a second cell containing: the first and second plasmids; and a fourth plasmid having an expression unit comprising a first nucleic acid molecule encoding a transcription activation domain operably linked to a second nucleic acid molecule encoding a mutant form of the post-translational modifier polypeptide that is defective or deficient in effecting post-translational modification of the target protein, wherein expression of the transcription activation domain and mutant post-translational modifier polypeptide in the cell produces a transcription activation domain-mutant post-translational modifier polypeptide fusion protein; culturing the first and second cells under conditions effective for post-translational modification of the target protein to occur; and determining reporter activity in the first and second cells, where an increase in reporter activity in the first cell as compared to the second cell indicates that the target protein has undergone post-translational modification by the post-translational modifier polypeptide molecule.