Characterization of mini-protein S, a recombinant variant of protein S that lacks the sex hormone binding globulin-like domain
| Autor: | Bonno N. Bouma, Rogier M. Bertina, Pieter H. Reitsma, Joost C. M. Meijers, J. G. Stam, G. T. G. Chang, M. Van Wijnen |
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| Rok vydání: | 1998 |
| Předmět: |
Integrin alphaXbeta2
Plasma protein binding Biochemistry Cofactor Epitope Protein S law.invention Cell Line Structure-Activity Relationship law Cricetinae Sex Hormone-Binding Globulin medicine Animals Humans Molecular Biology Blood Coagulation Factor VIIIa Sequence Deletion chemistry.chemical_classification biology Ligand binding assay Antibodies Monoclonal Cell Biology Molecular biology Recombinant Proteins chemistry Factor Va biology.protein Recombinant DNA Glycoprotein Carrier Proteins Protein C medicine.drug Protein Binding Research Article |
| Zdroj: | The Biochemical journal. 330 |
| ISSN: | 0264-6021 |
| Popis: | Protein S is a vitamin K-dependent glycoprotein involved in the regulation of the anticoagulant activity of activated protein C (APC). Also, an anticoagulant role for protein S, independent of APC, has been described. Protein S has a unique C-terminal sex hormone binding globulin (SHBG)-like domain that represents about half of the molecule. To define the role of this domain in APC cofactor activity and in binding to C4b-binding protein (C4BP), we have constructed a recombinant protein S molecule of N-terminal residues 1-242 that lacks the SHBG domain (mini-protein S). A panel of monoclonal antibodies directed against the N-terminal region of protein S recognized plasma-derived protein S, wild-type recombinant protein S and mini-protein S with similar affinities, whereas a monoclonal antibody that recognizes an epitope in the SHBG domain did not detect mini-protein S. Mini-protein S did not bind to C4BP in a solid-phase binding assay, and the cofactor activity of mini-protein S was not inhibited by preincubation with C4BP. In a plasma coagulation assay, the cofactor activity of mini-protein S was lower than wild-type or plasma-derived preparations. In contrast, no difference in APC cofactor activities was observed when the preparations were tested in purified systems that monitor the APC-mediated degradation of factors Va or VIIIa. In conclusion, we constructed a protein S molecule that fails to bind C4BP and still displays cofactor activity for APC. This confirms the role of the C-terminal SHBG region in C4BP binding and demonstrates that N-terminal residues 1-242 are sufficient for the expression of APC cofactor activity in a system using purified components. In plasma, however, the C-terminal SHBG region plays a role in the expression of optimal APC cofactor activity. |
| Databáze: | OpenAIRE |
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