G Protein-coupled Receptors From Structure to Function

G protein-coupled receptors (GPCRs) constitute the largest family of cell-surface receptors, with more than 800 members identified thus far in the human genome. They regulate the function of most cells in the body, and represent approximately 3% of the genes in the human genome. These receptors respond to a wide variety of structurally diverse ligands, ranging from small molecules, such as biogenic amines, nucleotides and ions, to lipids, peptides, proteins and even light. Ligands (agonists and antagonists) acting on GPCRs are important commonly used in drug therapy of numerous diseases, including cardiovascular and mental disorders, retinal degeneration, cancer, and AIDS. It is estimated that these receptors represent about one third of the actual identified targets of clinically used drugs. This book, which lies between the fields of chemical biology, molecular pharmacology and medicinal chemistry, is divided into three parts. The first part considers what receptor structures tell us about the mechanism of receptor activation. Part II focuses on receptor function. It discusses what the data from biophysical and mutational studies, and the analysis of the interactions of the receptor with ligands and regulator proteins, tell us about the process of signal transduction. The final part, on modelling and simulation, details what new insights on the link between structure and mechanism can be provided by theoretical studies and their implications in drug design. The various chapters present an update on the latest developments in GPCR structures and detailed structural changes linked to activation. They cover the latest news of the extraordinary complex function of these receptors, concentrating on the many aspects that are currently revolutionizing our current views of these proteins: receptor constitutive activity, receptor oligomerization, functional selectivity, biased agonism, multiple signalling pathways, multiple accessory proteins, functional cross talk and the mechanism of signal integration. This complex picture is tackled from complementary experimental and theoretical approaches, which represent a clear statement of our current knowledge of the GPCR complexity.