Necessary for signaling by class 3 semaphorins and subsequent remodeling of the cytoskeleton. Plays a role in axon guidance, neuronal growth cone collapse and cell migration. Homotetramer, and heterotetramer with CRMP1, DPYSL2, DPYSL4 or DPYSL5 (PubMed:9375656). Interacts with synaptic vesicle protein 2 and SH3A domain of intersectin (PubMed:12684468). Interacts with FLNA (By similarity). Colocalizes with synaptic vesicle protein 2 in the central region of the growth cone. Isoform 2 is expressed in growth cones. Up-regulated in motor neurons during axonal regeneration after sciatic nerve lesion. Overexpression of isoform 2 increased neurite extension and branching. Isoform 1 is expressed throughout neurons and their axons. At E17, isoform 2 is expressed in the CNS and PNS. Isoform 2 is expressed at high levels in the dorsal root ganglia, trigeminal ganglia, and throughout the spinal cord with the highest level in the ventral horn. Phosphorylation on Ser-522 by DYRK2 promotes subsequent phosphorylation on Thr-509, Thr-514 and Ser-518 by GSK3. Belongs to the metallo-dependent hydrolases superfamily. Hydantoinase/dihydropyrimidinase family. Lacks most of the conserved residues that are essential for binding the metal cofactor and hence for dihydropyrimidinase activity. Its enzyme activity is therefore unsure.