Identification of putative ligand binding sites within I domain of integrin α2β1 (VLA-2, CD49b/CD29)

Tetsuji Kamata, Wilma Puzon, Yoshikazu Takada

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Abstract

Integrin αβ1 is a cell surface adhesion receptor for collagen and echovirus 1. Here we localized the epitopes for anti-α2 monoclonal antibodies using interspecies (human/bovine) α2 chimeras with different lengths of human α2 sequence on the amino-terminal side and site-directed mutagenesis. The antibodies that block the collagen and/or echovirus 1 binding to human α2β1 (6F1, RMAC11, 12F1, and AA10) recognizes a small region (residues 173-259) within the I domain. Asp-160 and Arg-242 are critical for binding of the two other function-inhibiting antibodies, P1H5 and 5E8, respectively. Notably, mutations of Asp-151 and Asp-254 block the binding of α2β1 to collagen. These data suggest that the I domain (residues 140-359) is critically involved in the ligand/receptor interactions, and collagen and echovirus 1 binding sites are adjacent or overlapping within the I domain. The sequence of the residues 173-259 of α2 overlap with the peptide sequences (M11 and M20) that derive from von Willebrand factor A1 and A3 domains (homologous to the α2 I domain) and block von Willebrand factor/collagen interaction, suggesting that the epitope region of α2 (residues 173-259) may really be involved in ligand recognition.

Original languageEnglish
Pages (from-to)9659-9663
Number of pages5
JournalJournal of Biological Chemistry
Volume269
Issue number13
Publication statusPublished - Apr 1 1994
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry

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