Multiple discontinuous ligand-mimetic antibody binding sites define a ligand binding pocket in integrin α(IIb)β3

Wilma Puzon-McLaughlin, Tetsuji Kamata, Yoshikazu Takada

Research output: Contribution to journalArticle

86 Citations (Scopus)

Abstract

Integrin α(IIb)β3, a platelet fibrinogen receptor, is critically involved in thrombosis and hemostasis. However, how ligands interact with α(IIb)β3 has been controversial. Ligand-mimetic anti-α(IIb)β3 antibodies (PAC-1, LJ-CP3, and OP-G2) contain the RGD-like RYD sequence in their CDR3 in the heavy chain and have structural and functional similarities to native ligands. We have located binding sites for ligand-mimetic antibodies in α(IIb) and β3 using human-to-mouse chimeras, which we expect to maintain functional integrity of α(IIb)β3. Here we report that these antibodies recognize several discontinuous binding sites in both the α(IIb) and β3 subunits; these binding sites are located in residues 156-162 and 229230 of α(IIb) and residues 179-183 of β3. In contrast, several nonligand-mimetic antibodies (e.g. 7E3) recognize single epitopes in either subunit. Thus, binding to several discontinuous sites in both subunits is unique to ligand-mimetic antibodies. Interestingly, these binding sites overlap with several (but not all) of the sequences that have been reported to be critical for fibrinogen binding (e.g. N-terminal repeats 2-3 but not repeats 4-7, of a(IIb)). These results suggest that ligand-mimetic antibodies and probably native ligands may make direct contact with these discontinuous binding sites in both subunits, which may constitute a ligand-binding pocket.

Original languageEnglish
Pages (from-to)7795-7802
Number of pages8
JournalJournal of Biological Chemistry
Volume275
Issue number11
DOIs
Publication statusPublished - Mar 17 2000
Externally publishedYes

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Antibody Binding Sites
Integrins
Ligands
Binding Sites
Antibodies
Fibrinogen Receptors
Terminal Repeat Sequences
Platelets
Hemostasis
Fibrinogen
Epitopes
Thrombosis
Blood Platelets

ASJC Scopus subject areas

  • Biochemistry

Cite this

Multiple discontinuous ligand-mimetic antibody binding sites define a ligand binding pocket in integrin α(IIb)β3. / Puzon-McLaughlin, Wilma; Kamata, Tetsuji; Takada, Yoshikazu.

In: Journal of Biological Chemistry, Vol. 275, No. 11, 17.03.2000, p. 7795-7802.

Research output: Contribution to journalArticle

Puzon-McLaughlin, Wilma ; Kamata, Tetsuji ; Takada, Yoshikazu. / Multiple discontinuous ligand-mimetic antibody binding sites define a ligand binding pocket in integrin α(IIb)β3. In: Journal of Biological Chemistry. 2000 ; Vol. 275, No. 11. pp. 7795-7802.
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