Yeast two-hybrid assay identifies Rab-binding partners of the Drosophila GRIP domain proteins. (A) A representative yeast two-hybrid assay with part of the panel of Arf and Rab proteins. A full-length dGolgin-97 prey was tested against bait constructs for the indicated Arf and Rab proteins, which were either native (WT, wild type) or mutants expected to alter the nucleotide state T→N (GDP) or Q→L (GTP). The top panel shows the mating control, and the bottom panel shows the growth under selection for the HIS3 reporter gene. (B) Summary of the interactions found between the GRIP domain proteins and all of the small G proteins that showed a reaction with any of them. G proteins or their mutants that gave no reaction with any prey were omitted.