AMIGO family proteins are cell adhesion molecules that exhibit homophilic and heterophilic binding properties and are thought to play roles in neuronal axon tract development and cell adhesion. Members of the AMIGO family of type I transmembrane proteins contain 6 leucine-rich repeats (LRRs) and one Ig domain in the extracellular region. Amphoterin-Induced Gene and ORF 3 (AMIGO3) is a member of the AMIGO family of type I transmembrane proteins that contain 6 leucine-rich repeats (CRRs) and one Ig domain in their extracellular domains. It is ubiquitously expressed and is detected in all tissues studied. Mouse AMIGO3 shows less than 40% amino acid sequence homology with AMIGO1 and AMIGO2. The extracellular domain of mouse AMIGO3 shares 90% and 75% amino acid sequence identity with that of rat and human AMIGO3, respectively.