TABLE 1:
Proteins required for PSG formation identified in imaging screen with deletion collection.
| Gene product | % CP | % RP base | % RP lid | Granule |
|---|---|---|---|---|
| Ubiquitin-modifying proteins | ||||
| Doa1 | − | − | − | + |
| Ubi4 | − | − | − | + + + |
| Ubp6 | − | − | − | + + + |
| Regulators of energy levels | ||||
| Dnm1 | − | − | − | + |
| Hap4 | − | − | − | − |
| Hap5 | − | − | − | − |
| Kinases and phosphatases | ||||
| Nem1 | − | − | − | + |
| Npr3 | − | − | − | n.d. |
| Pak1 | + | − | + | + |
| Snf1 | + | − | − | + |
| DNA repair, chromatin remodeling | ||||
| Rad4 | + | − | − | − |
| Set3 | − | − | − | + |
| Snf5 | + | − | − | + |
| Snf6 | + | − | + | + |
| Sro9 | − | − | − | + |
| Proteins with miscellaneous functions | ||||
| Ade4 | − | − | − | + |
| Cpr7 | + | − | − | − |
| Icl1 | − | − | − | n.d. |
| Sec66 | − | − | + | − |
| Tps2 | − | − | − | − |
| Vps24 | + | − | − | + |
Null mutants of selected hit genes expressing either Pre2-, Rpn1-, or Rpn11-GFP were manually analyzed for PSG formation in quiescence. Two hundred cells were monitored by direct fluorescence microscopy. The percentage of cells that sequester CP, RP lid, and RP base into the PSG was counted. −, less than 30%, + between 30% and 50% of the respective proteasomal complex is sequestered into the PSGs.
The sequestration of the hit gene products into cytosolic granules in quiescence was analyzed by monitoring wild-type cells expressing GFP-labeled versions of the hit gene products, respectively. All protein granules formed by the respective GFP-labeled gene product were tested for reversibility upon exit from quiescence. Reversible and motile protein granules are designated in red (+), irreversible and immotile in black (+). Proteins colocalizing with PSGs were are designated (+ + +); n.d. the localization could not be detected.