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      The C-terminal region of laminin beta chains modulates the integrin binding affinities of laminins.

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          Abstract

          Laminins are major cell-adhesive proteins in basement membranes that are capable of binding to integrins. Laminins consist of three chains (alpha, beta, and gamma), in which three laminin globular modules in the alpha chain and the Glu residue in the C-terminal tail of the gamma chain have been shown to be prerequisites for binding to integrins. However, it remains unknown whether any part of the beta chain is involved in laminin-integrin interactions. We compared the binding affinities of pairs of laminin isoforms containing the beta1 or beta2 chain toward a panel of laminin-binding integrins, and we found that beta2 chain-containing laminins (beta2-laminins) bound more avidly to alpha3beta1 and alpha7X2beta1 integrins than beta1 chain-containing laminins (beta1-laminins), whereas alpha6beta1, alpha6beta4, and alpha7X1beta1 integrins did not show any preference toward beta2-laminins. Because alpha3beta1 contains the "X2-type" variable region in the alpha3 subunit and alpha6beta1 and alpha6beta4 contain the "X1-type" region in the alpha6 subunit, we hypothesized that only integrins containing the X2-type region were capable of discriminating between beta1-laminins and beta2-laminins. In support of this possibility, a putative X2-type variant of alpha6beta1 was produced and found to bind preferentially to beta2-laminins. Production of a series of swap mutants between the beta1 and beta2 chains revealed that the C-terminal 20 amino acids in the coiled-coil domain were responsible for the enhanced integrin binding by beta2-laminins. Taken together, the results provide evidence that the C-terminal region of beta chains is involved in laminin recognition by integrins and modulates the binding affinities of laminins toward X2-type integrins.

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          Author and article information

          Journal
          J Biol Chem
          The Journal of biological chemistry
          American Society for Biochemistry & Molecular Biology (ASBMB)
          0021-9258
          0021-9258
          Mar 20 2009
          : 284
          : 12
          Affiliations
          [1 ] Laboratory of Extracellular Matrix Biochemistry, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
          Article
          S0021-9258(20)32494-7
          10.1074/jbc.M809332200
          2658076
          19147489
          ea24f2e0-96c7-448e-92be-b348a3912ad6
          History

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