科研之友
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摘要
Background: Intracellular parts of GPCRs have yet to be effectively exploited as allosteric modulators. Results: The structure and mechanism of action of a lipidated pepducin agonist is determined. Conclusion: The pepducin requires the H8 helix and TM7 tyrosine propeller to stabilize the on-state and trigger receptor-G protein signaling. Significance: This work provides critical insight into the identification of allosteric modulators to this major drug target class. G protein-coupled receptors (GPCRs) are remarkably versatile signaling systems that are activated by a large number of different agonists on the outside of the cell. However, the inside surface of the receptors that couple to G proteins has not yet been effectively modulated for activity or treatment of diseases. Pepducins are cell-penetrating lipopeptides that have enabled chemical and physical access to the intracellular face of GPCRs. The structure of a third intracellular (i3) loop agonist, pepducin, based on protease-activated receptor-1 (PAR1) was solved by NMR and found to closely resemble the i3 loop structure predicted for the intact receptor in the on-state. Mechanistic studies revealed that the pepducin directly interacts with the intracellular H8 helix region of PAR1 and allosterically activates the receptor through the adjacent (D/N)PXXYYY motif through a dimer-like mechanism. The i3 pepducin enhances PAR1/G subunit interactions and induces a conformational change in fluorescently labeled PAR1 in a very similar manner to that induced by thrombin. As pepducins can potentially be made to target any GPCR, these data provide insight into the identification of allosteric modulators to this major drug target class.
- 出版日期2015-6-19
