Neural cell adhesion molecule involved in the dynamics of cell adhesion and in the generation of transmembrane signals at tyrosine kinase receptors. During brain development, critical in multiple processes, including neuronal migration, axonal growth and fasciculation, and synaptogenesis. In the mature brain, plays a role in the dynamics of neuronal structure and function, including synaptic plasticity. Interacts with SHTN1; the interaction occurs in axonal growth cones (PubMed:18519736). Interacts with isoform 2 of BSG (By similarity). Colocalized with SHTN1 in close apposition with actin filaments in filopodia and lamellipodia of axonal growth cones of hippocampal neurons (PubMed:18519736). Isoform 2 is predominantly found in the brain, while isoform 1 is found in the peripheral nervous system. Belongs to the immunoglobulin superfamily. L1/neurofascin/NgCAM family.