The RAS NanoBRET™ TE Assay utilizes the Promega NanoLuc® Binary Technology (NanoBiT®) PPI System to measure cellular target engagement at protein complexes. The NanoBiT® PPI System is structural complementation reporter that consists of two optimized subunits of the bioluminescent NanoLuc® Luciferase, LgBiT and SmBiT, which are fused to target proteins of interest. When these proteins interact, an active bioluminescent enzyme is reconstituted. When a NanoBRET™ Tracer binds one of these proteins in the complex, a BRET signal results. Using this approach, the RAS NanoBRET™ TE Assay quantifies compound affinity and fractional occupancy to RAS multimers.