Figure 6. Dhh1 and Pbp1 over-expression trigger Pab1 granule formation in the absence of stress.

Proteins were expressed under galactose-inducible promoters on high copy plasmids in wild-type cells. (A) Cells were assayed for their ability to form P-bodies (Edc3-mCherry) or stress granules (Pab1-GFP) in media containing 2% galactose with 0.25% sucrose. (B) Granules triggered by Dhh1 over-expression are dependent upon actively translating mRNAs. Addition of 100 µg/ml cycloheximide for 30 minutes to block translation following two hours of galactose induction substantially reduced Pab1 foci formation in cells over-expressing Dhh1, while only slightly reducing Pab1 foci in cells over-expressing Pbp1. (C) Pab1 over-expression does not cause granule formation as assessed by the P-body marker, Edc3, and the stress granule marker, Pbp1, in media containing 2% galactose with 0.25% sucrose. (*) denotes underestimate of Pab1 foci due to large string-like aggregation.