Table 1.
Member | Activity | Localization | Size (kDa) | Function |
---|---|---|---|---|
Sirt1 | DAC | Nucleus | 62 | Chromatin modulation, gene expression, senescence, apoptosis, insulin secretion, neuronal differentiation, adipogenesis, development, glucose metabolism |
Sirt2 | DAC and ART | Cytoplasmic | 41.5 | Cell cycle progression, adipocyte differentiation |
Sirt3 | DAC and ART | Mitochondria | 43.6 | Cellular metabolism, apoptosis |
Sirt4 | ART | Mitochondria | 35.2 | Regulation of insulin secretion, mitochondrial NAD(+) salvage |
Sirt5 | DAC | Mitochondria | 33.9 | Regulation of urea cycle |
Sirt6 | ART | Nucleus | 39.1 | Telomere maintenance, DNA repair |
Sirt7 | None | Nucleolus | 44.8 | rDNA transcription |
There are seven reported sirtuin enzymes in mammals that act as either a mono-ADP-ribosyl transferase (ART), a NAD+-dependent deacetylase (DAC), or both. Although each sirtuin enzyme has an NAD+-dependent catalytic core domain, the N-and/or C-terminal sequences are of variable lengths giving rise to specific sizes. Each sirtuin has a specific localization and function.