Platelet Fragmentation Requires a Specific Structural Conformation of Human Monoclonal Antibody against β3 Integrin
| Autor: | Simon Karpatkin, Ruimin Pan, Zongdong Li, Wei Zhang, Jing Wu, Michael A. Nardi |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Blood Platelets
Models Molecular Platelet Aggregation Protein Conformation medicine.drug_class Molecular Sequence Data Integrin Molecular Conformation Enzyme-Linked Immunosorbent Assay Monoclonal antibody Biochemistry Peptide Library medicine Humans Platelet Amino Acid Sequence Platelet activation Fragmentation (cell biology) Peptide library Molecular Biology Sequence Homology Amino Acid biology Chemistry Integrin beta3 Autoantibody Antibodies Monoclonal Cell Biology Platelet Activation Molecular biology Mutation biology.protein Antibody |
| Zdroj: | Journal of Biological Chemistry. 283:3224-3230 |
| ISSN: | 0021-9258 |
| Popis: | We have described an autoantibody against beta3 (GPIIIa49-66), a region of platelet integrin alphaIIbbeta3 that is unique. It induces platelet fragmentation in the absence of complement via antibody activation of platelet NADPH oxidase and 12-lipoxygenase to release reactive oxygen species, which destroy platelets. To study the mechanism of anti-GPIIIa antibody-induced platelet fragmentation, we screened a human single chain Fv antibody library with the GPIIIa49-66 peptide. Nine monoclonal antibodies were identified that were capable of binding to GPIIIa49-66. Surprisingly, binding avidity for GPIIIa49-66 did not correlate with activity of induction of platelet fragmentation. We therefore investigated the requirements for platelet fragmentation. Mutations were introduced into the heavy chain complementary-determining region-3 of clones 11, 43, and 54 by site-directed mutagenesis. The capability of these clones to induce platelet fragmentation or bind to GPIIIa49-66 subsequently changed. Molecular modeling of these clones with their mutants revealed that the ability to induce platelet fragmentation is affected by the side chain orientation of positively charged amino acids in the heavy chain of residues 99-102. Thus, a structural change in the conformation of anti-GPIIIa49-66 antibody contributes to its binding to the beta3 integrin and subsequent antibody-induced platelet fragmentation and aggregate dissolution. |
| Databáze: | OpenAIRE |
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