Presynaptic protein involved in both dopaminergic synaptic transmission and GABAergic system, thereby participating in the structural maturation of inhibitory interneuron synapses. Involved in the dopaminergic synaptic transmission by attenuating dopamine release through a presynaptic mechanism. Also participates in the GABAergic system (By similarity). Interacts with TIAM1. Specifically present within the presynaptic compartment of synapses. Belongs to the neurexin family. Extended N-terminus.