This gene is specifically expressed in the photoreceptors in the retina. The encoded product shares strong homology with the C. elegans unc119 protein and it can functionally complement the C. elegans unc119 mutation. It has been localized to the photoreceptor synapses in the outer plexiform layer of the retina, and suggested to play a role in the mechanism of photoreceptor neurotransmitter release through the synaptic vesicle cycle. Two transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Jul 2008].