crystal structure of the pac1r extracellular domain unifies a consensus fold for hormone recognition by class b g-protein coupled receptors水晶pac1r细胞外结构域结合激素的共识折叠识别,b类受体g蛋白耦合.pdf

Crystal Structure of the PAC1R Extracellular Domain Unifies a Consensus Fold for Hormone Recognition by Class B G-Protein Coupled Receptors 1,2 1¤ 1 2 1 Shiva Kumar , Augen Pioszak , Chenghai Zhang , Kunchithapadam Swaminathan *, H. Eric Xu * 1 Laboratory of Structural Sciences, Van Andel Research Institute, Grand Rapids, Michigan, United States of America, 2 Department of Biological Sciences, National University of Singapore, Singapore Abstract Pituitary adenylate cyclase activating polypeptide (PACAP) is a member of the PACAP/glucagon family of peptide hormones, which controls many physiological functions in the immune, nervous, endocrine, and muscular systems. It activates adenylate cyclase by binding to its receptor, PAC1R, a member of class B G-protein coupled receptors (GPCR). Crystal structures of a number of Class B GPCR extracellular domains (ECD) bound to their respective peptide hormones have revealed a consensus mechanism of hormone binding. However, the mechanism of how PACAP binds to its receptor remains controversial as an NMR structure of the PAC1R ECD/PACAP complex reveals a different topology of the ECD and a ˚ distinct mode of ligand recognition. Here we report a 1.9 A crystal structure of the PAC1R ECD, which adopts the same fold as commonly observed for other members of Class B GPCR. Binding studies and cell-based assays with alanine-scanned peptides and mutated receptor support a model that PAC1R uses the same conserved fold of Class B GPCR ECD for PACAP binding, thus unifying the consensus mechanism of hormone binding for this family of r