(A) Immunoblots and RNA gels showing polyadenylated mRNA isolated by oligo(dT) resin (left) or PABPC1 immunoprecipitation (right) pulling down poly-ubiquitinated proteins from HEK293T cells after 60 min heat shock. Isolated mRNA was visualized by SYBR orange RNA stain; arrow indicates high molecular weight RNA. (B) Quantification of immunoblot analysis for ubiquitin conjugation shown in (A). Results represent mean and individual values of 3 replicate experiments. Error bars indicate data range. (C) Scatter plot showing abundance (log2 [spectral counts]) of PABPC1-interacting proteins in heat shock versus control conditions. Results represent averages of 2 replicates. Lines indicate 2-fold increase (red) or decrease (blue) with heat shock; blue dots indicate heat shock ubiquitinome proteins. (D) Correlation between abundance of heat shock ubiquitinome proteins detected in TUBE pulldown and PABPC1 IP in 60 min heat-shocked samples. (E) Heatmap illustrating changes in abundance in 60 min heat shock versus control samples for proteins detected in TUBE pulldown, endogenous protein IP (PABP, SND1, GCN1, EIF4G, IPO4), or oligo(dT) pulldown.