Neuronal cell surface protein that may be involved in cell recognition and cell adhesion (By similarity). Plays a role in angiogenesis. A number of isoforms, alpha-type and beta-type are produced by alternative promoter usage. Beta-type isoforms differ from alpha-type isoforms in their N-terminus. Brain and arteries (at protein level). Proccessed by alpha-secretase leading to the formation of an extracellular soluble protein as well as a C-terminal membrane-embedded fragment (CTF). Proteolysis of these CTFs by gamma-secretase releases intracellular domains (ICDs) and extracellular peptides (By similarity). Produced by alternative promoter usage. Produced by alternative splicing of isoform 1b. Belongs to the neurexin family.