Epitope Mapping for Monoclonal Antibody Reveals the Activation Mechanism for αVβ3 Integrin

Tetsuji Kamata, Makoto Handa, Sonomi Takakuwa, Yukiko Sato, Yohko Kawai, Yasuo Ikeda, Sadakazu Aiso

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Epitopes for a panel of anti-αVβ3 monoclonal antibodies (mAbs) were investigated to explore the activation mechanism of αVβ3 integrin. Experiments utilizing αV/αIIb domain-swapping chimeras revealed that among the nine mAbs tested, five recognized the ligand-binding β-propeller domain and four recognized the thigh domain, which is the upper leg of the αV chain. Interestingly, the four mAbs included function-blocking as well as non-functional mAbs, although they bound at a distance from the ligand-binding site. The epitopes for these four mAbs were further determined using human-to-mouse αV chimeras. Among the four, P3G8 recognized an amino acid residue, Ser-528, located on the side of the thigh domain, while AMF-7, M9, and P2W7 all recognized a common epitope, Ser-462, that was located close to the α-genu, where integrin makes a sharp bend in the crystal structure. Fibrinogen binding studies for cells expressing wild-type αVβ3 confirmed that AMF-7, M9, and P2W7 were inhibitory, while P3G8 was non-functional. However, these mAbs were all unable to block binding when αVβ3 was constrained in its extended conformation. These results suggest that AMF-7, M9, and P2W7 block ligand binding allosterically by stabilizing the angle of the bend in the bent conformation. Thus, a switchblade-like movement of the integrin leg is indispensable for the affinity regulation of αVβ3 integrin.

Original languageEnglish
Article numbere66096
JournalPLoS One
Volume8
Issue number6
DOIs
Publication statusPublished - 2013 Jun 20
Externally publishedYes

Fingerprint

integrins
Integrins
Epitopes
monoclonal antibodies
Chemical activation
Monoclonal Antibodies
epitopes
chimerism
thighs
Ligands
Conformations
legs
fibrinogen
Propellers
crystal structure
Fibrinogen
epitope mapping
binding sites
Crystal structure
Binding Sites

ASJC Scopus subject areas

  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Epitope Mapping for Monoclonal Antibody Reveals the Activation Mechanism for αVβ3 Integrin. / Kamata, Tetsuji; Handa, Makoto; Takakuwa, Sonomi; Sato, Yukiko; Kawai, Yohko; Ikeda, Yasuo; Aiso, Sadakazu.

In: PLoS One, Vol. 8, No. 6, e66096, 20.06.2013.

Research output: Contribution to journalArticle

Kamata, Tetsuji ; Handa, Makoto ; Takakuwa, Sonomi ; Sato, Yukiko ; Kawai, Yohko ; Ikeda, Yasuo ; Aiso, Sadakazu. / Epitope Mapping for Monoclonal Antibody Reveals the Activation Mechanism for αVβ3 Integrin. In: PLoS One. 2013 ; Vol. 8, No. 6.
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