The SIRT3 gene encodes a member of the sirtuin family of proteins, homologs to the yeast Sir2 protein. The functions of human sirtuins have not yet been determined; however, yeast sirtuin proteins are known to regulate epigenetic gene silencing and suppress recombination of rDNA. Studies suggest that the human sirtuins may function as intracellular regulatory proteins with mono-ADP-ribosyltransferase activity. SIRT3 encodes a protein that is included in class I of the sirtuin family.