Fig. 4. ZYA stimulates mammalian 20S to degrade unstructured protein substrates.

a Mammalian 20S proteasomes (100 nM) incubated with tau23 (2uM). At the indicated times, the reaction was quenched by the addition of SDS loading buffer and separated by SDS-PAGE. Proteins visualized with Coomassie brilliant blue. Gels are representative of three independent experiments. 20S proteasome subunits are indicated with brackets to serve as loading controls for each sample. b Same as a, except with β-casein (1 uM). c ¹⁴C casein was incubated with mammalian 20S proteasome similar to D for 30 min at 37^oC.  Acid soluble counts after TCA precipitation were quantified via scintillation to show the generation of peptide products. p-value: 0.011. Data (means) are representative of three or more independent experiments each performed in triplicate. Error bars represent ± standard deviation.