Acetylcholinesterase
laminin binding
Human acetylcholinesterase binds to mouse laminin-1 and human collagen IV by an electrostatic mechanism at the peripheral anionic site.
Acetylcholinesterase (EC 3.1.1.7; AChE) is known to induce neurite outgrowth and differentiation, but its ligands are as yet unknown. Laminin-1 and collagen IV were investigated as potential ligands for AChE. We observed specific saturable binding of biotinylated human AChE to mouse laminin and human collagen, with K(d) values of 4.9482 nM (SE 0.3145 nM) and 1.1617 nM (SE 0.1921 nM) respectively. Peripheral anionic site inhibitors (fasciculin, BW284c51, propidium and gallamine) also significantly reduced binding with fasciculin being the most effective. Significant reductions in AChE-laminin and AChE-collagen interactions were produced by a monoclonal anti-AChE antibody known to react with the peripheral anionic site, and a partial reduction with an antibody that partially recognises the site. Self-association of AChE was also observed (K(d)=16.3235 nM; SE 5.8120 nM); increasing markedly at low pH, but not significantly affected by either inhibitors or antibodies, suggesting a non-specific aggregation phenomenon. Binding to laminin and collagen was significantly reduced by increasing ionic strength and decreasing pH, indicating a dominant role for electrostatic interactions, and suggesting that the site may be different from the hydrophobic site identified for the AChE-amyloid interaction.