We mammals have seven sirtuin genes that have evolved a variety of functions beyond what simple SIR2 can do. Three of them, SIRT1, SIRT6, and SIRT7, are critical to the control of the epigenome and DNA repair. The others, SIRT3, SIRT4, and SIRT5, reside in mitochondria, where they control energy metabolism, while SIRT2 buzzes around the cytoplasm, where it controls cell division and healthy egg production.
7 SIRs
