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Cover Picture: An Adaptable Luminescence Resonance Energy Transfer Assay for Measuring and Screening Protein–Protein Interactions and their Inhibition. (ChemBioChem 4/2012)
The cover picture shows the interaction of a green fluorescent protein (GFP) fusion (blue) with an Escherichia coli dihydrofolate reductase (eDHFR) fusion protein (red). Selective, noncovalent labeling of eDHFR with a trimethoprim (TMP)–terbium complex conjugate enables time-resolved, background-free detection of the long-lifetime (∼ms), terbium-to-GFP luminescence resonance energy transfer (LRET) signal, which indicates fusion protein interaction. On p. 553 ff, L. W. Miller et al. describe highly sensitive (signal-to-background ratio >100), LRET-based detection and accurate quantification of interactions between FK506 binding protein 12 (fused to GFP) and the rapamycin-binding domain of mTOR (fused to eDHFR) in impure bacterial lysates. TMP/eDHFR labeling can be easily adapted to develop high-throughput screening assays and complementary, quantitative counter screens for measuring interactions between a wide variety of protein targets that may not be amenable to purification.