The C-terminus of the gamma 2 chain but not of the beta 3 chain of laminin-332 is indirectly but indispensably necessary for integrin-mediated cell reactions

Exp Cell Res. 2008 Feb 1;314(3):489-97. doi: 10.1016/j.yexcr.2007.10.027. Epub 2007 Nov 12.

Abstract

Using a recombinant mini-laminin-332, we showed that truncation of the three C-terminal amino acids of the gamma 2 chain, but not of the C-terminal amino acid of the beta 3 chain, completely abolished alpha 3 beta 1 integrin binding and its cellular functions, such as attachment and spreading. However, a synthetic peptide mimicking the gamma 2 chain C-terminus did not interfere with alpha 3 beta 1 integrin binding or cell adhesion and spreading on laminin-332 as measured by protein interaction assays and electric cell-substrate impedance sensing. Nor was the soluble peptide able to restore the loss of integrin-mediated cell adhesiveness to mini-laminin-332 after deletion of the gamma 2 chain C-terminus. These findings spoke against the hypothesis that the gamma 2 chain C-terminus of laminin-332 is a part of the alpha 3 beta 1 integrin interaction site. In addition, structural studies with electron microscopy showed that truncation of the gamma 2 chain C-terminus opened up the compact supradomain structure of LG1-3 domains. Thus, by inducing or stabilizing an integrin binding-competent conformation or array of the LG1-3 domains, the gamma 2 chain C-terminus plays an indirect but essential role in laminin-332 recognition by alpha 3 beta 1 integrin and, hence, its cellular functions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence / physiology
  • Animals
  • Basement Membrane / metabolism*
  • Basement Membrane / ultrastructure
  • Binding Sites / physiology
  • Cell Adhesion / physiology
  • Cell Adhesion Molecules / chemistry
  • Cell Adhesion Molecules / genetics
  • Cell Adhesion Molecules / metabolism*
  • Cell Line
  • Cell Membrane / metabolism*
  • Cell Membrane / ultrastructure
  • Cell Movement / physiology
  • Epithelial Cells / metabolism*
  • Epithelial Cells / ultrastructure
  • Integrin alpha3beta1 / chemistry
  • Integrin alpha3beta1 / metabolism*
  • Kalinin
  • Microscopy, Electron, Transmission
  • Protein Binding / physiology
  • Protein Structure, Tertiary / physiology
  • Protein Subunits / chemistry
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Rats
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism

Substances

  • Cell Adhesion Molecules
  • Integrin alpha3beta1
  • Protein Subunits
  • Recombinant Fusion Proteins