Arf-like proteins (ARLs) are ubiquitously expressed small G proteins of the RAS superfamily. In photoreceptors, ARL2 and ARL3 participate in the trafficking of lipidated membrane-associated proteins and colocalize in the inner segment with UNC119A and PDEδ. UNC119A and PDEδ are acyl- and prenyl-binding proteins, respectively, involved in trafficking of acylated (transducin-α subunit, nephrocystin NPHP3) and prenylated proteins (GRK1, PDE6). Germline Arl3 knockout mice do not survive beyond postnatal day 21 and display ciliary defects in multiple organs (kidney, liver and pancreas) as well as retinal degeneration. Conditional knockouts will be necessary to delineate mechanisms of protein transport in retina disease.
Keywords: Arf-like protein 2 (ARL2); Arf-like protein 3 (ARL3); Phosphodiesterase δ-subunit (PDEδ); Retinitis pigmentosa protein 2 (RP2); Rod photoreceptor; unc-119 homolog (C. elegans) (UNC119A).