Fig. 4.

Protein half-lives are longer (turnover is slower) throughout the cell in CR mice than in AL. A, Selected functional classes like the 40S ribosomal subunit and some classes of cytosolic proteins are less perturbed than the average, whereas the mitochondrial proteins are affected to a greater degree. B, Comparison of the half-life (t ½, calculated as ln(2)/k) for proteins associated with specific organelles. Boxes show the interquartile range for protein turnover in the organelle. Bars extend to 5% and 95% of the data, with outliers as points. Only proteins that were solely and unambiguously assigned to the indicated organelle were used. Although the median half-life was systematically longer in CR, only the mitochondrial proteins were statistically significant (Student's two-tailed heteroscedastic t test, ** p < 0.005).