Contactin 2 (CNTN2, transiently-expressed axonal glycoprotein, AXT, TAX, TAX1, TAG-1, axonin 1) is a neuronal cell adhesion molecule (CAM) that influences the formation of axon connections in the developing nervous system. Contactin 2 is a member of the immunoglobulin superfamily (IgSF) and contains a glycosylphosphatidylinositol-anchor, six immunogobulin (Ig)-like and four Fibronectin type III (FNIII)-like domains. Contactin 2 is expressed predominantly during neural development on the cell membrane of axons in nerve fiber tracts in order to guide commissural axons without promoting their growth. Contactin 2 binds with NgCAM in the plane of the same membrane (cis-binding). The Contactin 2 heterophilic (Contactin 2/NgCAM and Contactin 2/NrCAM) binding sites are localized to the first four Ig domains. The Contactin 2 homophilic (Contactin 2/Contactin 2) binding site is localized to the FNIII domain.