LAUSR

The protein p73 acts as a transcription factor, resulting in tumour suppression. MDM2, an oncogenic protein, can negatively influence p73‐mediated apoptosis by binding to p73 transactivation domains (TAD). Inhibition of the protein‐protein interaction between p73 and oncogenic proteins is an attractive strategy for promoting p73‐mediated apoptosis. Herein, we describe the use of a modified p73‐TAD peptide for the FRET‐based assay of the binding of p73‐TAD to MDM2. The FRET probe, equipped with 1‐naphthylamine (λex=330 nm, λem=445 nm), serves as a FRET acceptor, and the tryptophan of the protein acts as FRET donor (λex=280 nm, λem=340 nm). Sensitized emission from the FRET probe was observed upon excitation of the protein‐FRET‐probe complex at the excitation wavelength of Trp. Furthermore, addition of the MDM2 inhibitor Nutiln‐3 drastically reduced the FRET signal, thus indicating that the FRET probe competes with Nutiln‐3 for MDM2 binding. The developed FRET binding assay might be applicable in high‐throughput screening of novel drugs that inhibit interactions between p73 and MDM2.