Mapping of the laminin-binding site of the N-terminal agrin domain (NtA)

Joseph B. Mascarenhas, Markus A. Rüegg, Uwe Winzen, Willi Halfter, Jürgen Engel, Jörg Stetefeld

Research output: Contribution to journalArticlepeer-review

34 Scopus citations

Abstract

Agrin is a key organizer of acetylcholine receptor (AChR) clustering at the neuromuscular junction. The binding of agrin to laminin is required for its localization to synaptic basal lamina and other basement membranes. The high-affinity interaction with the coiled-coil domain of laminin is mediated by the N-terminal domain of agrin. We have adopted a structurally guided site-directed mutagenesis approach to map the laminin-binding site of NtA. Mutations of L117 and V124 in the C-terminal helix 3 showed that they are crucial for binding. Both residues are located in helix 3 and face the groove between the β-barrel and the C-terminal helical segment of NtA. Remarkably, the distance between both residues matches a heptad repeat distance of two aliphatic residues which are solvent exposed in the coiled-coil domain of laminin. A lower but significant contribution originates from R43 and a charged cluster (E23, E24 and R40) at the open face of the β-barrel structure. We propose that surface-exposed, conserved residues of the laminin γ1 chain interact with NtA via hydrophobic and ionic interactions.

Original languageEnglish (US)
Pages (from-to)529-536
Number of pages8
JournalEMBO Journal
Volume22
Issue number3
DOIs
StatePublished - Feb 3 2003
Externally publishedYes

Keywords

  • Agrin
  • Basal lamina
  • Coiled coil
  • Laminin
  • Neuromuscular junction

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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