Fig. 6: Characterization of proteasome accumulation and activity.

a Quantitative determination of proteasome subunits by proteome-wide protein quantification¹⁸ of the indicated genotypes and after the indicated treatment (DMSO control, +MG132). The ppm values for all subunits belonging to the lid (upper panel), the base (middle panel) and the 20S catalytic core (lower panel) from three biological and three technical replicates were summed up and the results are presented along with their standard deviation (SD). The annotation of subunits to the lid, the base and the core is as published previously¹⁷. Significant differences are indicated with one (p-value < 0.05, T-test, two-sided) or two (p-value < 0.01) stars (two-sided T-test). b Chymotrypsin activity of the proteasome reported in RFU/min as determined from extracts of ppi2 and rpn8a ppi2 mutants (error-bars represent SD, note that the differences are not significant). c Hypocotyl length determination from wildtype and rpn8a single mutants from 5-day old etiolated seedlings, presented as the mean from 24 plants, grown in the presence of the indicated amount of MG132 (error-bars represent SD). Significant differences are indicated with one (p-value < 0.005) or two (p-value < 0.001) stars (two-sided T-test). d Quantitative real-time transcript abundance determination for different lid, base, 20S subunits and regulatory components (“other”) from wildtype and rpn8a mutant plants. Error-bars represent SD. Significant differences are indicated with one (p-value < 0.05) or two (p-value < 0.01) stars (two-sided T-test). e Relationship between transcriptional regulation (y-axis: Log2-transcript ratio from the double mutant in relation to the ppi2 single mutant) and protein abundance (x-axis: Log2-protein abundance ratio from the double mutant in relation to the ppi2 single mutant) for three proteasome subunits (gray), two regulatory factors (orange) and three photosynthetic proteins (green) for comparison.