4xt1
From Proteopedia
Structure of a nanobody-bound viral GPCR bound to human chemokine CX3CL1
Structural highlights
Function[US28_HCMVA] Receptor for a C-C type chemokine. Binds to a number of different CC-chemokines including CCL5/RANTES, CCL2/MCP-1, CCL3/MIP-1-alpha as well as CX3CL1/Fractalkine. Transduces signals resulting in the activation of MAP kinase signaling pathways and augmentation of intracellular calcium ion levels, leading to alterations in chemotactic behavior of vascular smooth muscle cells and macrophages. The US28 receptor also exhibits high levels of agonist-independent signaling activity and agonist-independent endocytosis. Interacts with endogenous Gaq/11 subunits and thereby constitutively activates phospholipase C.[1] [2] [X3CL1_HUMAN] The soluble form is chemotactic for T-cells and monocytes, but not for neutrophils. The membrane-bound form promotes adhesion of those leukocytes to endothelial cells. May play a role in regulating leukocyte adhesion and migration processes at the endothelium. Binds to CX3CR1.[3] Publication Abstract from PubMedChemokines are small proteins that function as immune modulators through activation of chemokine G protein-coupled receptors (GPCRs). Several viruses also encode chemokines and chemokine receptors to subvert the host immune response. How protein ligands activate GPCRs remains unknown. We report the crystal structure at 2.9 angstrom resolution of the human cytomegalovirus GPCR US28 in complex with the chemokine domain of human CX3CL1 (fractalkine). The globular body of CX3CL1 is perched on top of the US28 extracellular vestibule, whereas its amino terminus projects into the central core of US28. The transmembrane helices of US28 adopt an active-state-like conformation. Atomic-level simulations suggest that the agonist-independent activity of US28 may be due to an amino acid network evolved in the viral GPCR to destabilize the receptor's inactive state. Structural biology. Structural basis for chemokine recognition and activation of a viral G protein-coupled receptor.,Burg JS, Ingram JR, Venkatakrishnan AJ, Jude KM, Dukkipati A, Feinberg EN, Angelini A, Waghray D, Dror RO, Ploegh HL, Garcia KC Science. 2015 Mar 6;347(6226):1113-7. doi: 10.1126/science.aaa5026. PMID:25745166[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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