UNC-69 does not interact with ARL-1, ARL-3 or ARFRP. (a) Plasmids containing LexA-unc-69 or LexA-human SCOCO were cotransformed into yeast cells with vector alone or vectors containing GAD-unc-76γ, GAD-arl-1, GAD-arl-3, or GAD-arfrp. Protein-protein interactions were measured as β-galactosidase activity by using ONPG liquid assays. UNC-69 did not interaction with any of the three ARL proteins. SCOCO did not interact with any of the three ARL proteins either (data not shown). (b) Auxotrophic growth assays for interactions between LexA-UNC-119 and GAD-ARL-3 or GAD-UNC-76γ. Cells (3 × 104) were plated onto +His or -His plates, and serial tenfold dilutions of cells were then subsequently plated. Cells were grown at 30°C for 48 h before images were taken. Note that the -His plate did not contain 3-amino triazol. The strength of interaction between UNC-119 and ARL-3Δ17 was only a fifth of that between UNC-119 and ARL-3 FL, as assayed by β-galactosidase activity (data not shown).