4qt5 | pdb_00004qt5

Crystal Structure of 3BD10: A Monoclonal Antibody against the TSH Receptor

spinqualitylabelsall models 4qt5, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4qt5 is a 4 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed The TSH receptor (TSHR) A-subunit is more effective than the holoreceptor in inducing thyroid-stimulating antibodies (TSAb) that cause Graves' disease. A puzzling phenomenon is that 2 recombinant, eukaryotic forms of A-subunits (residues 22-289), termed active and inactive, are recognized mutually exclusively by pathogenic TSAb and mouse monoclonal antibody 3BD10, respectively. Understanding the structural difference between these TSHR A-subunit forms could provide insight into Graves' disease pathogenesis. The 3-dimensional structure of the active A-subunit (in complex with a human TSAb Fab, M22) is known, but the structural difference with inactive A-subunits is unknown. We solved the 3BD10 Fab 3-dimensional crystal structure. Guided by prior knowledge of a portion of its epitope, 3BD10 docked in silico with the known active TSHR-289 monomeric structure. Because both TSAb and 3BD10 recognize the active TSHR A-subunit monomer, this form of the molecule can be excluded as the basis for the active-inactive dichotomy, suggesting, instead a role for A-subunit quaternary structure. Indeed, in silico analysis revealed that M22, but not 3BD10, bound to a TSHR-289 trimer. In contrast, 3BD10, but not M22, bound to a TSHR-289 dimer. The validity of these models is supported experimentally by the temperature-dependent balance between active and inactive TSHR-289. In summary, we provide evidence for a structural basis to explain the conformational heterogeneity of TSHR A-subunits (TSHR-289). The pathophysiologic importance of these findings is that affinity maturation of pathogenic TSAb in Graves' disease is likely to involve a trimer of the shed TSHR A-subunit. Crystal structure of a TSH receptor monoclonal antibody: insight into Graves' disease pathogenesis.,Chen CR, Hubbard PA, Salazar LM, McLachlan SM, Murali R, Rapoport B Mol Endocrinol. 2015 Jan;29(1):99-107. doi: 10.1210/me.2014-1257. PMID:25419797 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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