TAG-1 can mediate homophilic binding, but neurite outgrowth on TAG-1 requires an L1-like molecule and beta 1 integrins

Neuron. 1994 Mar;12(3):675-90. doi: 10.1016/0896-6273(94)90222-4.


Subsets of axons in the embryonic nervous system transiently express the glycoprotein TAG-1, a member of the subfamily of immunoglobulin (Ig)-like proteins that contain both C2 class Ig and fibronectin type III domains. TAG-1 is attached to the cell surface by a glycosylphosphatidylinositol linkage and is secreted by neurons. In vitro studies have shown that substrate-bound TAG-1 promotes neurite outgrowth. We have examined the nature of axonal receptors that mediate the neurite-outgrowth promoting properties of TAG-1. Although TAG-1 can mediate homophilic binding, neurite outgrowth on a substrate of TAG-1 does not depend on the presence of TAG-1 on the axonal surface. Instead, neurite outgrowth on TAG-1 is inhibited by polyclonal antibodies directed against L1 and, independently, by polyclonal and monoclonal antibodies against beta 1-containing integrins. These results provide evidence that TAG-1 can interact with cell surfaces in both a homophilic and heterophilic manner and suggest that neurite extension on TAG-1 requires the function of both integrins and an L1-like molecule.

Publication types

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

MeSH terms

  • Animals
  • Antibodies / immunology
  • Cell Adhesion Molecules, Neuronal / pharmacology
  • Contactin 2
  • Extracellular Matrix Proteins / pharmacology
  • Ganglia, Spinal / drug effects
  • Ganglia, Spinal / ultrastructure
  • Integrins / immunology
  • Integrins / physiology*
  • Leukocyte L1 Antigen Complex
  • Membrane Glycoproteins / immunology
  • Membrane Glycoproteins / pharmacology*
  • Nerve Tissue Proteins / pharmacology
  • Neurites / drug effects
  • Neurites / metabolism*
  • Neurites / physiology*
  • Rats
  • Substrate Specificity
  • Tenascin


  • Antibodies
  • Cell Adhesion Molecules, Neuronal
  • Contactin 2
  • Extracellular Matrix Proteins
  • Integrins
  • Leukocyte L1 Antigen Complex
  • Membrane Glycoproteins
  • Nerve Tissue Proteins
  • Tenascin