Target Protein of Interest (POI)

Target Protein of Interest (POI) is a ubiquitous term in drug discovery and chemical biology used to denote a specific protein that is the focus of therapeutic intervention or experimental study [1, 5]. In the field of targeted protein degradation (TPD), the POI is the substrate recruited by heterobifunctional molecules, such as PROTACs, to an E3 ubiquitin ligase for subsequent polyubiquitination and proteasomal degradation [10, 15]. This approach allows for the modulation of proteins previously considered "undruggable," such as transcription factors or non-enzymatic scaffolding proteins, by utilizing proximity-induced mechanisms rather than direct functional inhibition [12, 30]. The selection of a POI is a critical step in drug development, requiring validation of its pathological role in diseases like cancer, neurodegeneration, or inflammation [6, 12]. Because the term is a generic placeholder, the specific biological functions, disease associations, and pharmacological profiles are defined by the actual protein (e.g., BRD4, AR, or EGFR) being targeted in a particular therapeutic program [14, 15].

Other names

Protein of InterestPOITarget Protein

Variable (depends on the specific protein being targeted)