Molecular Dissection of the α-Dystroglycan- and Integrin-binding Sites within the Globular Domain of Human Laminin-10

Hiroyuki Ido, Kenji Harada, Sugiko Futaki, Yoshitaka Hayashi, Ryoko Nishiuchi, Yuko Natsuka, Shaoliang Li, Yoshinao Wada, Ariana C. Combs, James M. Ervasti, Kiyotoshi Sekiguchi

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The adhesive interactions of cells with laminins are mediated by integrins and non-integrin-type receptors such as α-dystroglycan and syndecans. Laminins bind to these receptors at the C-terminal globular domain of their α chains, but the regions recognized by these receptors have not been mapped precisely. In this study, we sought to locate the binding sites of laminin-10 (α5β1y1) for α3β1, and α6β1 integrins and α-dystroglycan through the production of a series of recombinant laminin-10 proteins with deletions of the LG (laminin G-like) modules within the globular domain. We found that deletion of the LG4-5 modules did not compromise the binding of laminin-10 to α3β1 and α 6β1 integrins but completely abrogated its binding to α-dystroglycan. Further deletion up to the LG3 module resulted in loss of its binding to the integrins, underlining the importance of LG3 for integrin binding by laminin-10. When expressed individually as fusion proteins with glutathione S-transferase or the N-terminal 70-kDa region of fibronectin, only LG4 was capable of binding to α-dystroglycan, whereas neither LG3 nor any of the other LG modules retained the ability to bind to the integrins. Site-directed mutagenesis of the LG3 and LG4 modules indicated that Asp-3198 in the LG3 module is involved in the integrin binding by laminin-10, whereas multiple basic amino acid residues in the putative loop regions are involved synergistically in the α-dystroglycan binding by the LG4 module.

Original languageEnglish (US)
Pages (from-to)10946-10954
Number of pages9
JournalJournal of Biological Chemistry
Issue number12
StatePublished - Mar 19 2004
Externally publishedYes


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