Structural and Functional Analysis of a β₂-Adrenergic Receptor Complex with GRK5

다국어 초록 (Multilingual Abstract)

<P><B>Summary</B></P> <P>The phosphorylation of agonist-occupied G-protein-coupled receptors (GPCRs) by GPCR kinases (GRKs) functions to turn off G-protein signaling and turn on arrestin-mediated signaling. While a structural understanding of GPCR/G-protein and GPCR/arrestin complexes has emerged in recent years, the molecular architecture of a GPCR/GRK complex remains poorly defined. We used a comprehensive integrated approach of cross-linking, hydrogen-deuterium exchange mass spectrometry (MS), electron microscopy, mutagenesis, molecular dynamics simulations, and computational docking to analyze GRK5 interaction with the β<SUB>2</SUB>-adrenergic receptor (β<SUB>2</SUB>AR). These studies revealed a dynamic mechanism of complex formation that involves large conformational changes in the GRK5 RH/catalytic domain interface upon receptor binding. These changes facilitate contacts between intracellular loops 2 and 3 and the C terminus of the β<SUB>2</SUB>AR with the GRK5 RH bundle subdomain, membrane-binding surface, and kinase catalytic cleft, respectively. These studies significantly contribute to our understanding of the mechanism by which GRKs regulate the function of activated GPCRs.</P> <P><B>PaperClip</B></P> <P>Display Omitted</P> <P><B>Highlights</B></P> <P> <UL> <LI> GRK5-β<SUB>2</SUB>AR binding is enhanced by receptor and kinase ligands and acidic lipids </LI> <LI> GRK5 binding to the β<SUB>2</SUB>AR involves a multi-site interaction </LI> <LI> Receptor binding triggers substantial conformational changes in GRK5 </LI> <LI> RH/catalytic domain separation in GRK5 is essential for receptor phosphorylation </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>