A biased allosteric modulator functions as a molecular glue to induce β2AR dimerization

  • bioRxiv. 2025 Oct 22:2025.10.21.683802. doi: 10.1101/2025.10.21.683802.
Jiemin Shen  1  2 ,  Teja Nikhil Peddada  1  2 ,  Konstantin E Komolov  3  2 ,  Francesco De Pascali  3  2 ,  Alexander M Garces  4 ,  Haoqing Wang  1 ,  Michael T Lerch  4 ,  Jeffrey L Benovic  3 ,  Jun Xu  5 ,  Brian K Kobilka  1  6
Affiliations
  • 1. Department of Molecular and Cellular Physiology, Stanford University School of Medicine, 279 Campus Drive, Stanford, CA 94305, USA.
  • 2. These authors contributed equally.
  • 3. Department of Biochemistry and Molecular Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA.
  • 4. Department of Biophysics, Medical College of Wisconsin, Milwaukee, WI, USA.
  • 5. Department of Medical Neuroscience, SUSTech Homeostatic Medicine Institute, School of Medicine, Institute for Biology Electron Microscopy, Southern University of Science and Technology, Shenzhen, Guangdong, 518067, China.
  • 6. Lead contact.
PMID: 41279134 DOI: 10.1101/2025.10.21.683802
Abstract

Family A G-protein coupled receptors (GPCRs) are typically described as monomers, yet growing evidence suggests they can form dimers with distinct signaling properties1-3. The mechanisms and therapeutic potential of such dimerization, however, remain poorly understood. Here, we show that AP-7-168, an optimized derivative of a β-arrestin-biased negative allosteric modulator of the β2-adrenergic receptor (β2AR) that sustains bronchorelaxation in cell and tissue models4, functions as a molecular glue to promote β2AR homodimerization. Cryo-EM structures reveal a unique binding mode in which two AP-7-168 molecules pack within a pocket formed by transmembrane helices 3, 4, and 5 of two protomers, stabilizing a dimeric conformation that selectively prevents β-arrestin coupling. In cells, AP-7-168 robustly induces β2AR dimerization and drives enlarged nanocluster formation. Combined with extensive functional studies, our findings unveil a novel allosteric mechanism by which a small molecule biases β2AR signaling through dimerization, highlighting ligand-induced dimerization as a strategy for GPCR modulation.

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