Structure of the receptor-binding domain of human thrombopoietin determined by complexation with a neutralizing antibody fragment
| Autor: | Atsushi Matsumoto, Kinya Ogami, Tomoyuki Tahara, Takashi Kato, Hiroshi Miyazaki, Hiroshi Watarai, Michael D. Feese, Taro Tamada, Yoshitake Maeda, Hideki Shigematsu, Yasuko Matsukura, Ryota Kuroki, Takanori Muto, Yoichi Kato, Masako Hirose |
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| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular Stereochemistry Protein Conformation Molecular Sequence Data Plasma protein binding Crystallography X-Ray Substrate Specificity Epitopes Immunoglobulin Fab Fragments Structure-Activity Relationship Protein structure Neutralization Tests Proto-Oncogene Proteins Structure–activity relationship Humans Amino Acid Sequence Receptors Cytokine Neutralizing antibody Peptide sequence Multidisciplinary biology Chemistry Biological Sciences Ligand (biochemistry) Neoplasm Proteins Biochemistry Solubility Thrombopoietin biology.protein Cytokine receptor Receptors Thrombopoietin Protein Binding |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America. 101(7) |
| ISSN: | 0027-8424 |
| Popis: | The cytokine thrombopoietin (TPO), the ligand for the hematopoietic receptor c-Mpl, acts as a primary regulator of megakaryocytopoiesis and platelet production. We have determined the crystal structure of the receptor-binding domain of human TPO (hTPO 163 ) to a 2.5-Å resolution by complexation with a neutralizing Fab fragment. The backbone structure of hTPO 163 has an antiparallel four-helix bundle fold. The neutralizing Fab mainly recognizes the C–D crossover loop containing the species invariant residue Q111. Titration calorimetric experiments show that hTPO 163 interacts with soluble c-Mpl containing the extracellular cytokine receptor homology domains with 1:2 stoichiometry with the binding constants of 3.3 × 10 9 M –1 and 1.1 × 10 6 M –1 . The presence of the neutralizing Fab did not inhibit binding of hTPO 163 to soluble c-Mpl fragments, but the lower-affinity binding disappeared. Together with prior genetic data, these define the structure–function relationships in TPO and the activation scheme of c-Mpl. |
| Databáze: | OpenAIRE |
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