structural basis for the tethered peptide activation of adhesion gpcrs peptide activation - melanotan-peptide-side-effects Adhesion G protein-coupled receptors Unraveling the Structural Basis for the Tethered Peptide Activation of Adhesion GPCRs

structure-d-un-peptide The intricate world of cell signaling is constantly revealing new mechanisms by which cells communicate and respond to their environment.Mechanism of Tethered Agonist Binding to an Adhesion G- ... Among these, adhesion GPCRs (aGPCRs), a unique class of G protein-coupled receptors, have emerged as critical players in diverse physiological processes. A significant breakthrough in understanding their function lies in deciphering the structural basis for the tethered peptide activation of adhesion GPCRs. This activation mechanism, driven by an internal peptide sequence, is fundamental to the receptor's ability to transduce signals across the cell membrane.

At the heart of this activation process is the concept of tethered peptide activation.作者：YQ Ping·2022·被引用次数：126—Many aGPCRs are activated by a conserved internal (tethered) agonist sequence known as the Stachel sequence7-12. Unlike many other GPCRs that require external ligands for activation, aGPCRs possess an intrinsic activating element, often referred to as a Stachel sequence. This sequence, a conserved internal peptide, remains concealed until specific cellular events trigger its exposure. Once decrypted, this tethered peptide acts as an agonist, directly engaging and activating the receptor. This self-activating property is a defining characteristic of adhesion GPCRs, distinguishing them from other GPCR families.

Recent advancements, particularly in techniques like cryogenic electron microscopy (cryo-EM), have provided unprecedented insights into the structural basis of this phenomenon.Structural basis for the tethered peptide activation of ... Studies have revealed the structures of various aGPCRs in complex with their activating peptides and downstream signaling partners, such as Guanine nucleotide-binding protein G(s) subunit alpha isoforms short (Gs).作者：N Wang·2023·被引用次数：14—Recentstructuraladvancements in aGPCRs research have led to the elucidation of thetethered-peptide activationmechanism of aGPCRs. However, ... These high-resolution structures allow researchers to visualize the precise interactions between the tethered peptide and the receptor's transmembrane domain. For instance, the structural basis for the tethered peptide activation of adhesion GPCRs has been elucidated for receptors like GPR133 and GPR114, showing how the Stachel sequence penetrates the seven-transmembrane (7TM) orthosteric binding pocket.作者：X Zhu·2022·被引用次数：46—The stalkpeptideadopts twofold helix into the orthosteric ligand binding pocket formed by TM1,2,3,5,6,7 and ECL1,2,3 (Fig. 2a). The ligand ...

The peptide activation mechanism involves the Stachel sequence adopting a specific conformation, often a partial alpha-helical fold, within the binding pocketStructural basis of tethered agonism and G protein coupling of .... This interaction stabilizes the receptor in an active state, enabling it to couple with intracellular G proteins, most notably Gs.(PDF) Structural basis of adhesion GPCR GPR110 ... The decrypted TA penetrates the 7TM orthosteric binding pocket where it adopts a partial $\alpha$-helical fold to stabilize an active conformation.作者：X Zhu·2022·被引用次数：46—The stalkpeptideadopts twofold helix into the orthosteric ligand binding pocket formed by TM1,2,3,5,6,7 and ECL1,2,3 (Fig. 2a). The ligand ... This structural basis of tethered agonism and G protein coupling is crucial for initiating downstream signaling cascades that influence a multitude of cellular functions, including cell adhesion, migration, and differentiation.

Furthermore, the tethered peptide activation mechanism of adhesion GPCRs is intimately linked to the receptor's own processing. Many adhesion GPCRs undergo autoproteolytic cleavage within their extracellular domains, particularly within the GAIN domainStructural basis of CD97 activation and G-protein coupling. This cleavage event is often a prerequisite for the Stachel sequence to become accessible for activationUpon dissociation of the N-terminal fragment, the C-terminus of the GAIN domain acts as atetheredagonist (TA)peptideto activate the seven-transmembrane .... For example, it has been demonstrated that GPR114 is a self-cleaved adhesion GPCR, and this cleavage is essential for its tethered peptide agonist to activate the receptor. The C-terminus of the GAIN domain, upon dissociation of the N-terminal fragment, acts as the tethered agonist peptide (TA)Structural basis for the tethered peptide activation of adhesion ....

The structural basis of GAIN domain autoproteolysis and activation is an active area of research, with studies focusing on the intricate details of this self-processing event. Understanding this process is key to comprehending how the receptor is poised for activation. The tethered agonist then interacts with the receptor's seven-transmembrane domain, leading to conformational changes that facilitate G protein coupling. This intricate interplay between extracellular domain processing and transmembrane domain activation highlights the sophisticated regulatory mechanisms governing adhesion G-protein coupled receptors.The structure of the ADGRG2(FL)–IP15–Gs complex reveals thestructural basisfor the improved binding affinity of IP15 compared with VPM–p15 and indicates that ...

The elucidation of the structural basis for the tethered peptide activation of adhesion GPCRs has not only advanced our fundamental understanding of GPCR biology but also opened new avenues for therapeutic intervention. By understanding the precise molecular interactions involved, researchers can design specific modulators, such as peptidic antagonists, to target these receptors for various diseases. The development of such modulators, as seen in efforts to generate peptidic antagonists towards several aGPCRs by converting "finger residues" to acidic residues, underscores the translational potential of this research. The structural clarity achieved in studying these receptors provides a solid foundation for future drug discovery efforts targeting these vital cell surface proteins.

In summary, the structural basis for the tethered peptide activation of adhesion GPCRs is a complex and elegant mechanism involving an internal peptide agonist, the Stachel sequence, which becomes exposed upon specific cellular events. The detailed structures obtained through cryo-EM have illuminated how this tethered peptide interacts with the receptor to induce activation and subsequent G protein coupling. This discovery is fundamental to understanding the diverse roles of adhesion GPCRs in health and disease, paving the way for novel therapeutic strategies. The activation of these receptors through their intrinsic tethered peptide highlights their unique role in cellular communication and their importance as therapeutic targets.