Structure and Function Studies of GPCRome - PROJECT SUMMARY/ABSTRACT G Protein-Coupled Receptors (GPCRs) are integral to numerous physiological processes, orchestrating complex intracellular signaling cascades through their coupling with heterotrimeric G proteins (G proteins). Their paramount significance in pharmacology, as prime targets for drug development due to their easy accessibility and established therapeutic efficacy, elevates the comprehensive understanding of GPCR signaling pathways among the highest public health research priorities. The crucial role of G proteins in determining physiological functions and drug efficacy has traditionally led to the classification of GPCRs into four main groups based on their G protein coupling preferences: Gi/o-, Gq-, Gs-, and G12/13-coupled receptors. However, recent developments have revealed that this simple conventional taxonomy falls short in capturing the full spectrum of physiological functions mediated by GPCRs. This gap in our understanding presents significant challenges in advancing drug development and highlights the urgent need for a deeper investigation into the true signaling capabilities of GPCRs. Our trailblazing research seeks to bridge the historical knowledge gap in GPCR functionality. We have ignited new studies revealing a complexity in GPCRs that was previously underestimated. Moving beyond past beliefs, our findings demonstrate that GPCRs can activate a wide range of G proteins across different subfamilies. This discovery highlights the promiscuity of GPCRs, uncovering a complex network of signaling pathways that remain largely unexplored. Alongside our discoveries, advancements in structural biology have clarified the intricate ways GPCRs interact with G proteins. Yet, key details of G protein selectivity interactions still await discovery. Our proposal aims to illuminate key aspects of GPCR function and structure by combining bioinformatics with a novel enzymological approach in living cells. Moving beyond traditional methods, our innovative approach involves directly measuring the enzymatic activity of GPCRs to gain precise, quantitative insights into G protein selectivity. We plan to categorize GPCRs based on this newfound selectivity data, exploring the structural underpinning behind their specific protein preferences. To deepen our understanding of selective GPCR/G protein interactions, this process will involve a comprehensive computational analysis, utilizing both existing structures and predictive models. Our research adopts a holistic approach to demystify the multifaceted function and architecture of GPCRs. This strategy is poised to transform our comprehension of their involvement in various physiological activities. By revealing these detailed interactions, our work lays the groundwork for advancing basic scientific research and developing innovative pharmacological methods. This foundational study opens the door for further exploration into the selective manipulation of G protein coupling, potentially catalyzing significant breakthroughs in therapeutic interventions.
