Biological significance of protein modifications in aging and calorie restriction.

By virtue of the progress in proteomics, the involvement of posttranslational modifications in aging has been more clearly demonstrated in recent years. We describe here that (1) carbonylation, a hallmark of protein oxidation in general, is paradoxically decreased in histone with aging and increased by calorie restriction (CR), (2) acetylation of lysine 9 and phosphorylation of serine 10 in histone H3 are decreased and increased, respectively, with aging, and (3) the acetylation level of multiple extranuclear proteins decreases significantly with aging, and the change was not only retarded but increased remarkably by CR in rat liver. Based on these findings, we discuss possible implications of the posttranslational protein modifications in biochemical processes underlying aging and CR-induced extension of life span.