Promotes growth and fasciculation of neurites from cultured hippocampal neurons. May be involved in fasciculation as well as myelination of developing neural axons. May have a role in regeneration as well as neural plasticity in the adult nervous system. May mediate homophilic as well as heterophilic cell-cell interaction and contribute to signal transduction through its intracellular domain (By similarity). Assembled with KCNB1 modulates the gating characteristics of the delayed rectifier voltage-dependent potassium channel KCNB1 (PubMed:22056818). Homodimer, and heterodimer with AMIGO2 and AMIGO3 (PubMed:21983541). Interacts with KCNB1 (PubMed:22056818). Colocalizes with KCNB1 at high-density somatodendritic clusters on the surface of hippocampal and cortical neurons (PubMed:22056818). Associated with axons of neuronal cells (By similarity). Expressed in hippocampal and cortical neurons (at protein level) (PubMed:22056818). High levels in cerebellum, cerebrum, and retina. Low levels in liver, kidney, small intestine, spleen, lung and heart. The LRR repeat region mediates homodimerization. Belongs to the immunoglobulin superfamily. AMIGO family.