Cell adhesion-like membrane protein of the central nervous system (CNS) which modulates both the position and complexity of central neurons by altering their membrane morphology and dynamics. Involved in the formation of neuronal dendrites and protrusions including dendritic filopodia. In synaptogenesis, regulates synapse formation by altering dendritic spine morphology and actin distribution. Promotes formation of unstable neuronal spines such as thin and branched types. Regulates neuronal morphogenesis and migration during cortical development in the brain. Can homooligomerize through cis interactions within the same cell membrane. N-glycosylated. Extended N-terminus.