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. Highly expressed in the central nervous system (CNS), with the highest expression in thalamus, hippocampus, cerebrum, midbrain and spinal cord. Also highly expressed in stomach, kidney and small intestine. Expressed in the ventral spinal cord, with strong expression in a subset of motor neurons, and in a subset of sensory neurons at embryonic day (E) 15.5 (PubMed:25826454). In the developing brain, expressed at low levels on 11 dpc, rapidly increasing to peak at postnatal day (P) 1, a period corresponding to the early stage of postmitotic neuronal differentiation when neuronal morphogenesis or synapse formation occurs, and then gradually decreasing (PubMed:27683913). N-glycosylated. RNAi-mediated knockdown mice have significantly lower density of dendritic filopodia and dendritic spines in embryonic hippocampal neurons. Lower density of excitatory synapses and significantly decreased dendritic spine to shaft ratio of F-actin in the later stages of neuron development. Aberrant neuronal migration in the cerebral cortex of developing mouse embryo. Neurons settle in the marginal zone (MZ) closer to the pial side and the corresponding percentage of neurons is decreased in the dense cortical plate (dCP), reflecting the overmigration of those neurons. Neurons in the upper cortical plate (UCP) result in a small but significant reduction in both the number of dendrites and average dendrite length. Neurons of embryonic brains show much lower levels of spines with the density of mushroom spines markedly decreased.