Expression and subcellular distribution of UNC119a, a protein partner of transducin α subunit in rod photoreceptors

► UNC119 is enriched in the inner segment of rod photoreceptors. ► UNC119a distribution in rods is consistent with its role in transducin trafficking. ► The estimated molar ratio of UNC119a to transducin is ~ 1 to 4. ► UNC119a is downregulated in the absence of transducin-α. ► Light-translocated transducin-α is apparently a major binding partner for UNC119a.