Strains deleted for PB host factors are defective at different stages.

<p>WT (BY4741) and deletion strains were induced with α-factor for 8 h <b>(A, C, and D)</b> and 0, 2 and 6 h <b>(B)</b>. Statistical significance was determined using the R statistical computing package (<a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1005528#pgen.1005528.s014" target="_blank">S1 Text</a>, Supplemental Materials and Methods). <b>(A)</b> Total Ty3 RNA levels. RNA was isolated and quantified by northern blotting. WT Ty3 RNA signal was normalized to that of control <i>snR17a</i>. <b>(B)</b> Ty3 protein expression. Ty3 proteins were detected using α-CA. Pgk1 was detected with α-Pgk1 and used as a loading control. Data are representative of two or more independent inductions. Ty3 Gag3 protein levels were normalized to Pgk1 and averaged. <b>(C)</b> Ty3 RNA packaging. Native extracts were nuclease treated to degrade unpackaged RNA or left untreated. Ty3 RNA generated by <i>in vitro</i> transcription was added to the extract to monitor RNA digestion. Following treatment, RNA was purified and quantified by northern blotting. The percentage of Ty3 RNA resistant to degradation was calculated. <b>(D)</b> Ty3 cDNA synthesis. Cells were induced with α-factor for 8 h. DNA was isolated and digested with <i>Nhe</i>I and <i>Bam</i>HI restriction enzymes. Ty3 endogenous elements and cDNA were detected by Southern blot. Genomic <i>ARG4</i> was used as a loading control.