Fig 5.

Rtf1 is required for efficient recruitment of the 19S proteasome to the GAL1 ORF. (A) Expression level of Flag-tagged Rpt1 in wild-type (WT) and rtf1 deletion mutant strains. Samples were analyzed by SDS-PAGE and Western blotting. Cdc28 (Cdk1) was used as a loading control. (B) Recruitment of Flag-tagged Rpt1 to the GAL1 ORF in the absence of Rtf1. Before and after galactose induction for 45 min, chromatin immunoprecipitation using anti-Flag antibodies was performed in wild-type untagged protein (control), wild-type Rpt1-Flag, and rtf1 Rpt1-Flag. Rpt1-associated chromatin fragments were isolated, amplified using the indicated primers, and normalized to the amount of input DNA prior to immunoprecipitation. All error bars represent SD. Statistical analysis was carried out comparing WT and Δrtf1. P values determined using Student's t test. (C) Model for Cks1-mediated transcription. We propose that Cks1 functions as an adaptor for recruiting the 19S proteasome to Rtf1 in order to promote efficient transcription elongation.