Figure 1.

Application of the yeast two-bait interaction trap to the analysis of phosphotyrosine-dependent protein–protein interactions. (A) Standard yeast two-bait interaction trap. (B) Modified yeast two-bait interaction trap. In both systems, a bait₂ is substituted by a PTK that tyrosine-phosphorylates the bait₁ component of a TetR-bait₁ hybrid localized to a TetOp-URA3 reporter. Phosphorylation of bait₁ allows interaction with a prey protein and subsequent URA3 gene transcription. In the standard system the PTK is fused to LexA and is not targeted within the cell. In the modified system the PTK is also fused to TetR, resulting in juxtaposition of the PTK to bait₁.