The conformational–condensate code of GRB2: State switching, spatial organization, and therapeutic windows

Growth factor receptor-bound protein 2 (GRB2) is a core adaptor protein that coordinates signals from receptor tyrosine kinases, immune receptors, and metabolic pathways, triggering context-specificcellular responses linked to both normal physiology and disease. While GRB2 has long been defined by its classic interactions—specifically, the binding of its SH2 domain to phosphotyrosine residues and its SH3 domains to proline-rich motifs—emerging research has increasingly revealed it to be a dynamic signaling hub, whose function is governed by conformational switching, inter-domain allostery, and the assembly of biomolecular condensates. Through a combination of structural and biochemical studies, we have come to understand that the equilibria between GRB2 monomers and dimers, domain swapping events, and post-translational modifications work in concert to fine-tune the specificity of its signaling, creating a direct mechanistic link between GRB2 and the development of oncogenesis, immune dysregulation, and insulin resistance. Beyond its well-characterized role in the cytoplasm, GRB2 also localizes to key subcellular compartments including endosomes, lipid rafts, and the nucleus, where it plays a critical role in mediating DNA damage responses. The diversity of GRB2 isoforms, most notably the splice variant Grb3-3, further reshapes cellular signaling networks by modulating the availability of SOS (Son of Sevenless), with far-reaching implications for the pathogenesis of cancer, diabetes, and autoimmune disorders. We propose the “conformational–condensate code” to unify GRB2 regulatory logic: its intrinsic conformational shifts and subcellular condensate assembly jointly determine signaling thresholds under healthy and diseased conditions. From a therapeutic perspective, GRB2 has emerged as a versatile and promising target, with strategies ranging from the inhibition of its SH2 and SH3 domains to allosteric modulation, condensate-directed pharmacology, and the restoration of isoform balance. Notably, antisense oligonucleotides such as prexigebersen (BP1001) have advanced to clinical trials, demonstrating favorable safety profiles and early signs of anti-leukemic activity, while BP1001-A is currently being developed for the treatment of obesity-associated type 2 diabetes—findings that underscore the broad translational potential of targeting GRB2 across a spectrum of diseases.