Figure 4. The polyQ-rich region of Cbk1 alters Htt103Q toxicity and aggregation.

(A) Impact of indicated Cbk1 truncations or mutations upon Htt103Q toxicity as monitored via growth assays plated in 5-fold dilutions. Cbk1(1–326) is the polyQ-rich region of the protein, and Cbk1(327–756) lacks this region. (B) Cbk1-mRFP and Cbk1(1–326)-mRFP co-localize with Htt103Q in distinct foci. Cbk1 constructs were expressed from a copper inducible promoter induced with 100 uM CuSO₄ for 5 h total and Htt103Q was induced with 2% galactose for 4 h total. Nuclei were visualized with DAPI staining.