HETEROPHILIC INTERACTIONS OF THE NEURAL CELL-ADHESION MOLECULES NG-CAM AND NR-CAM WITH NEURAL RECEPTORS AND EXTRACELLULAR-MATRIX PROTEINS

Ng-CAM/L1 and Nr-CAM are closely related neural cell adhesion molecule s expressed on neurons and Schwann cells. Ng-CAM/L1 is prevalent on ax ons and is a potent promoter of neurite growth and axonal fasciculatio n. Although Nr-CAM does not appear to play a major role in these funct ions, its transient expression in the developing floor plate of the sp inal cord is important for guidance of commissural axons. Ng-CAM and N r-CAM can bind homophilicly and heterophilicly to several adhesion mol ecules. Different complexes of adhesion molecules are likely to contro l axonal growth and guidance as a consequence of their differential lo calizations in vivo.