The polyglutamine-rich (polyQ) domain of Def1 mediates its interaction with mRNA regulators and recruits the translation regulator Dhh1 to ribosomes. (A) BioID was conducted with Def1 truncation mutants fused to TID. Labeled proteins that were enriched for each Def1 derivative versus free TID (>1.5-fold, P < 0.05) were tabulated. The numbers and percentages of RNA regulators and ribosome-associated factors identified in the SGD database were calculated and displayed in the table. Dhh1 binds to ribosomes in a def1Δ (B) and not4Δ (C) mutant. (D) MS2–MCP tethering assay for GFP protein expression. MCP or MCP–Def1 were expressed in DHH1 (black bars) or dhh1Δ (gray bars) cells as indicated in the panel. The amount of GFP protein in cells expressing “free” MCP was set to 1.0. The averages and standard deviations of three biological replicates (N = 3) are displayed. (***) P < 0.001
