Fig. 5.

Krr1 is required for recruitment of Rps1, Rps14 and UTP-C to the 90S pre-ribosome. a Depletion of Krr1 causes recruitment defects of the UTP-C complex, Rps14, and Rps1 to the 90S pre-ribosome. A yeast Krr1 degron strain (scKrr1-HA₃-AID) expressing integrated scUtp10-FTpA and scUtp22-myc were grown in YPD medium, before degradation of Krr1 was induced by addition of indole-3-acetic acid (Auxin) to the medium and further growth for 90 min. Subsequently, scUtp10-FTpA was affinity-purified and the eluates derived from the non-depleted and Krr1-depleted strains, respectively, were analyzed by SDS-PAGE (4–12%) and Coomassie staining (upper panel), or western blotting (lower panel) using the indicated antibodies. Dashed box is a zoom of the respective gel region to better display the Utp22/Rps1 depletion. Indicated proteins were identified via mass spectrometry. b Krr1 forms a complex with Utp22 and Rrp7 in vitro. The indicated ctUtp22-Rrp7-Krr1 complex was assembled by co-expression of the corresponding Chaetomium thermophilum factors in yeast followed by split-tag tandem affinity-purification. The final eluate was analyzed by SDS-PAGE (4–12%) and Coomassie staining. Labeled bands were verified by mass spectrometry identification. The experiments were performed at least twice with consistent results. Uncropped images are shown in Supplementary Fig. 9. S molecular weight protein standard, E eluate