Further characterization of the loop structure of platelet glycoprotein IIIa: partial mapping of functionally significant glycoprotein IIIa epitopes
| Autor: | W C, Kouns, P J, Newman, K J, Puckett, A A, Miller, C D, Wall, C F, Fox, J M, Seyer, L K, Jennings |
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| Rok vydání: | 1991 |
| Předmět: |
Blood Platelets
Protein Conformation Blotting Western Immunoblotting Molecular Sequence Data Immunology Antibodies Monoclonal Platelet Membrane Glycoproteins Cell Biology Hematology Flow Cytometry Peptide Mapping Biochemistry Peptide Fragments Molecular Weight Epitopes Kinetics Chymotrypsin Humans Amino Acid Sequence |
| Zdroj: | Blood. 78:3215-3223 |
| ISSN: | 1528-0020 0006-4971 |
| Popis: | Glycoprotein (GP) IIb-IIIa serves as the platelet fibrinogen receptor. Studies of the tertiary structure of GPIIIa have shown that the protein has a large loop structure of at least 325 amino acids in length. To further characterize this loop structure, intact platelets were digested with alpha-chymotrypsin. Digestion products were examined using the anti-GPIIIa monoclonal antibodies (MoAbs) AP3, D3GP3, and C5GP3, as well as the human alloantibody, anti-PLA1. AP3 recognized GPIIIa digestion products of 109, 95, and 68 Kd. D3GP3 and C5GP3 recognized an additional band of 51 Kd. Time course digestions demonstrated that the 51-Kd fragment was generated by proteolysis of the 68-Kd peptide. Sequence analysis of the reduced 51-Kd peptide showed that this fragment began at amino acid 422. The nonreduced 51-Kd peptide was reactive with antibodies directed against the first 13 amino acids of GPIIIa, demonstrating the presence of a covalently attached N-terminal peptide. These data suggest that: (1) the minimum length of the loop structure is at least 384 amino acids; (2) the AP3 epitope is formed at least in part by a determinant contained within residues 348 to 421; and (3) the D3GP3 and C5GP3 epitopes are contained within amino acids 422 to 692 of GPIIIa, a region that may be flexible and involved in conformational changes that occur after ligand binding. |
| Databáze: | OpenAIRE |
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