SIRT7 is a member of the sirtuin family of proteins (Sir2-like proteins). All Sir2-like proteins are characterized by a sirtuin core domain and grouped into four classes. The functions of human sirtuins are not fully understood yet. Recent studies sμggested that bacterial, yeast and mammalian sirtuins are able to metabolize NAD and may function as intracellular regulatory proteins with mono-ADP-ribosyltransferase activity.