Figure 2.

Schematic overview of human sirtuins and their PTMs. The seven mammalian sirtuins are schematically indicated with the blue boxes depicting the sirtuin-typic catalytic core domain. The catalytic domains are flanked by distinct N- and C-terminal extensions (gray boxes). The numbers below indicate amino acid numbers for orientation. Two isoforms (IF) are shown for SIRT2 and SIRT5, respectively. The ESA (“essential for SIRT1 activity”) sequence of SIRT1 (see below) is indicated. PTMs, nuclear localization sequences, nuclear export sequences, and proteolytic cleavage sites are indicated. The precise amino acids modified by the different PTMs are given in Table 1.