Contactin-associated protein-like 4 is a protein  belongs to the neurexin family, members of which function in the vertebrate nervous system as cell adhesion molecules and receptors. This protein, like other neurexin proteins, contains epidermal growth factor repeats and laminin G domains. In addition, it includes an F5/8 type C domain, discoidin/neuropilin- and fibrinogen-like domains, and thrombospondin N-terminal-like domains. CASPR4 was expressed at variable levels in all brain tissues examined, with highest expression in the subthalamic nucleus and substantia nigra. In situ hybridization and immunohistochemical analyses revealed high expression of CASPR4 in specific neuronal subpopulations in the olfactory bulb, hippocampus, deep cerebellar nuclei, and substantia nigra.