Research Paper Volume 5, Issue 11 pp 802—812

Figure 4. Proteasome function is diminished in aged cells.

(A) Degradation of the in vivo UPS substrate ub-P-βgal over time in young and aged (~13-15 generations) cells after the inhibition of protein synthesis. The starting β-gal levels were set to 1. The figure depicts representative results from one out of six independent experiments (P=7.38^E-06). (B) Relative levels of Rpt1p (19S subunit), 20S core proteins, and 26S proteasomes (based on native gels) in aged cells compared to young cells (n≥3). (C) Proteasomal capacity in total protein extracts measured as the rate of hydrolysis of the fluorogenic peptide suc-LLVY-AMC (Chymotryptic activity) depicted as the specific activity (nmol AMC/min*mg total protein). A representative figure is presented (n=3). (D) Rpt6-GFP (19S subunit) localization in young and aged (~13-15 generations) cells. Error bars represent standard deviation. For statistical analysis, the paired two-tailed t-test was used where *P<0.05, **P<0.01, ***P<0.001 and n.s = no significant difference. (n= sets of analysis; Scale-bars represent 10μm.