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 (By similarity). Homotetramer, and heterotetramer. At 16 hours post-fertilization, expressed in the presumptive nucleus of the medial longitudinal fascicle, the presumptive trigeminal ganglion and the spinal cord. Expression in the spinal cord is strongest towards the rostral, more mature, spinal cord, and weaker towards the caudal spinal cord. At 24 hours post-fertilization, expressed in the olfactory placode, in the telencephalon and diencephalon but not in the proliferating ventricular zone. Expressed in the epiphysis, the nucleus of the medial longitudinal fascicle and in the area close to the nucleus of the posterior commissure. Expression in the hindbrain is restricted to reticulospinal neurons. In the cranial ganglia, expressed in the trigeminal, acoustic/anterior lateral line and posterior lateral line ganglion. In the spinal cord, expressed in the large dorsally-located Rohon-Beard neurons. 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.