SIRT6 encodes a member of the sirtuin family of proteins, homologs to the yeast Sir2 protein. Members of the sirtuin family are characterized by a sirtuin core domain and grouped into four classes. 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. The protein encoded by this gene is included in class IV of the sirtuin family.Sirtuins can be divided into 4 main classes in eukaryotes based on amino acid sequence motifs, with yeast Sir2 belonging to class Ia. The deduced 355-amino acid SIRT6 protein is a class IV sirtuin, a class not present in prokaryotes.