
Drug discovery researchers face a fundamental constraint in their work to develop safe, effective therapeutics: the vast majority of the human proteome remains inaccessible to conventional small molecule approaches. Proteins without defined binding pockets, those lacking known chemical probes, and protein targets that fail to translate from biochemical assays into cellular models have long been considered out of reach of standard drug discovery screening tools. As Dixit et al. describe, developing biochemical or cellular assays for all genome-encoded targets “is not scalable and likely impossible as most proteins have ill-defined or unknown activity” — these are what the authors call “the dark undruggable expanses” of the proteome [1].
That gap is now narrowing. Promega Corporation recently launched the TarSeer™ BRETSA™ Target Engagement System, a live-cell target engagement platform designed to bring previously challenging targets within reach of early-stage drug discovery.
The Problem: A Translation Gap in Early Discovery
Drug discovery teams regularly encounter a frustrating disconnect. A compound may show strong binding activity in a biochemical assay, only to fail when tested in a cellular environment. Without target-specific cellular assays, which generally aren’t available for poorly characterized proteins, researchers face difficult choices when deciding which compounds to advance through the drug development pipeline.
Continue reading “Why BRETSA™ Target Engagement Matters for Drug Discovery”







