Low nidogen affinity of laminin-5 can be attributed to two serine residues in EGF-like motif gamma 2III4

FEBS Lett. 1995 May 29;365(2-3):129-32. doi: 10.1016/0014-5793(95)00438-f.

Abstract

High affinity nidogen binding of laminin-1 (chain composition alpha 1 beta 1 gamma 1) has been previously mapped to a single EGF-like motif gamma 1III4 of its gamma 1 chain. Two more isoforms, laminin-5 (alpha 3 beta 3 gamma 2) and laminin-7 (alpha 3 beta 2 gamma 1), show low and high binding activity, respectively, indicating that the gamma 2 chain is of low affinity. This was confirmed by recombinant production of the homologous EGF-like motif gamma 2III4 of the gamma 2 chain, which has a 100,000-fold lower binding activity than gamma 1III4. The crucial heptapeptide binding sequence Asn-Ile-Asp-Pro-Asn-Ala-Val of gamma 1III4 is modified in gamma 2III4 by replacing both the central Asn and Val by Ser. Changing these replacements to Asn and Val by site-directed mutagenesis enhanced the activity of gamma 2III4 to a level which was only 5-fold lower than that of gamma 1III4. Despite their high sequence identity (77%) motifs gamma 1III4 and gamma 2III4 were also shown to differ considerably in immunological epitopes. This indicates distinctly different functions for laminins which differ in the gamma chain isoform.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Asparagine
  • Base Sequence
  • Basement Membrane / metabolism
  • Binding Sites
  • Cell Adhesion Molecules / chemistry*
  • Cell Adhesion Molecules / metabolism*
  • Cell Line
  • DNA Primers
  • Epidermal Growth Factor / chemistry*
  • Humans
  • Kinetics
  • Membrane Glycoproteins / chemistry*
  • Membrane Glycoproteins / metabolism*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Point Mutation
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid
  • Serine*
  • Transfection
  • Valine

Substances

  • Cell Adhesion Molecules
  • DNA Primers
  • Membrane Glycoproteins
  • Recombinant Proteins
  • kalinin
  • nidogen
  • Serine
  • Epidermal Growth Factor
  • Asparagine
  • Valine