sirtuin

(redirected from Sir2 proteins)
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Related to Sir2 proteins: Sirtuin, SIRT1, SIRT2, HP1

sirtuin

(sûr′to͞o-ĭn, -tyo͞o-)
n.
Any of a family of enzymes that occur in all living organisms and are thought to regulate cellular aging, apoptosis, and resistance to stress in more complex eukaryotic organisms.
Any of a class of proteins that possess either histone deacetylase—more commonly—or mono-ribosyltransferase activity, named after Sir2, the cell-regulating yeast gene silent mating-type information regulation 2. Sirtuins regulate critical biological pathways in eubacteria, archaea and eukaryotes.
Sirtuins influence ageing, transcription, apoptosis, stress resistance, and affect energy efficiency and alertness during hypoglycaemia
Most sirtuins are protein deacetylases in which sirtuin-mediated deacetylation couples lysine deacetylation to NAD hydrolysis—instead of simple hydrolysis of acetyl-lysine residues—yielding O-acetyl-ADP-ribose, the deacetylated substrate and nicotinamide. The dependence of sirtuins on NAD links their enzymatic activity directly to the energy status of the cell via the cellular NAD:NADH ratio, the absolute levels of NAD, NADH or nicotinamide or a combination of these variables.

sirtuin

(sĭr′too-ĭn)
Any of a class of proteins that are coded by the SIR family of genes. These proteins contribute to chromosome repair and may have a role in extending the life span of cells.
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