The AP3B2 gene encodes a neuron-specific subunit of the heterotetrameric Adaptor protein-3 (AP3) vesicle-coat protein complex. The complex is required for intracellular protein transport, particularly post-Golgi vesicle-mediated transport and anterograde synaptic vesicle transport. It has been found that the interaction of neuronal AP3 with vesicles regulates vesicle neurotransmitter content.
The gene is associated with Epileptic Encephalopathy, Early Infantile, 48 (EIEE48), a severe neurologic disorder characterized by intellectual disability, global developmental delay, seizures, microcephaly and absent speech.