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Modern drug discovery relies on combinatorial screening campaigns to find drug molecules targeting specific disease-associated proteins. The success of such campaigns often relies on functional and structural information of the selected therapeutic target, only achievable once its purification is mastered. With the aim of bypassing the protein purification process to gain insights on the druggability, ligand binding, and/or characterization of protein–protein interactions, herein, we describe the Extract2Chip method. This approach builds on the immobilization of site-specific biotinylated proteins of interest, directly from cellular extracts, on avidin-coated sensor chips to allow for the characterization of molecular interactions via surface plasmon resonance (SPR). The developed method was initially validated using Cyclophilin D (CypD) and subsequently applied to other drug discovery projects in which the targets of interest were difficult to express, purify, and crystallize. Extract2Chip was successfully applied to the characterization of Yes-associated protein (YAP): Transcriptional enhancer factor TEF (TEAD1) protein–protein interaction inhibitors, in the validation of a ternary complex assembly composed of Dyskerin pseudouridine synthase 1 (DKC1) and RuvBL1/RuvBL2, and in the establishment of a fast-screening platform to select the most suitable NUAK family SNF1-like kinase 2 (NUAK2) surrogate for binding and structural studies. The described method paves the way for a potential revival of the many drug discovery campaigns that have failed to deliver due to the lack of suitable and sufficient protein supply.

Eukaryotic initiation factor 2B (eIF2B), a guanine nucleotide exchange factor (GEF), promotes protein synthesis by charging translation initiation factor 2 (eIF2) with GTP. Stress-induced phosphorylation of eIF2 on its α-subunit [eIF2(αP)] inhibits this reaction triggering a protective Integrated Stress Response (ISR). A DNA-encoded chemical library (DEL) screen for modulators of eIF2B, led to the identification of a chemical series that stabilises the inactive state of eIF2B, stimulating the ISR. Cryo-EM of compound-bound eIF2B reveals a conformational switch to the inactive state engaged by eIF2(αP). In cells, compound activity is sensitive to eIF2’s phosphorylation state and to a competing eIF2B ligand (ISRIB) that activates the GEF allosterically. These findings establish the feasibility of targeting eIF2B with a drug-like allosteric inhibitor, that serves as an ISR activator (ISRAC), paving the way to explore the therapeutic potential of eIF2B-directed ISR activation. Protein synthesis is tightly regulated by the integrated stress response, but therapeutic activation remains challenging. Here, the authors identify a drug‑like allosteric inhibitor, an ISRAC, that stabilises inactive eIF2B, mimicking stress‑induced eIF2α phosphorylation to activate the ISR, establishing eIF2B as a tractable target for ISR modulation.

Eukaryotic initiation factor 2B (eIF2B), a guanine nucleotide exchange factor (GEF), promotes protein synthesis by charging translation initiation factor 2 (eIF2) with GTP. Stress-induced phosphorylation of eIF2 on its α-subunit [eIF2(αP)] inhibits this reaction triggering a protective Integrated Stress Response (ISR). A DNA-encoded chemical library (DEL) screen for modulators of eIF2B, led to the identification of a chemical series that inactivates eIF2B, stimulating the ISR. Cryo-EM of compound-bound eIF2B revealed a conformational switch to the inactive state engaged by eIF2(αP). In cells, compound activity was sensitive to eIF2’s phosphorylation state and to a competing eIF2B ligand (ISRIB) that activates the GEF allosterically. These findings mark the discovery of a first-in-class drug-like allosteric inhibitor of eIF2B, an ISR activator (ISRAC), paving the way to explore the therapeutic potential of eIF2B-directed ISR activation.