Phosphorylation Regulates SIRT1 Function
Figure 1
A. Affinity-purified SIRT1 is phosphorylated, and can be dephosphorylated by λppase. Top panel, western blot of total SIRT1; middle panel, western blot of SIRT1 phosphorylated at the Cdk consensus site; bottom panel, ProQ-diamond stained blot showing total phosphorylated SIRT1. Numbers above the lanes indicate the relative doses of λppase used to treat FLAG-SIRT1 for 1 hour. Overnight treatment (O/N) was done with a 1/10 dilution of λppase. B. Schematic of the phosphorylated residues in SIRT1 identified by mass spectrometry, as shown in Table 1. P, phosphorylated residue. C. 3D structure prediction of full-length human SIRT1 with the positions of phosphorylated residues identified by mass spectrometry (red symbols). Amino terminal domain, green; catalytic core domain, blue; carboxy terminal domain, yellow. The Rossmann fold supporting the catalytic groove in the core domain is shown in red. The two mutated residues described in the text (Thr530 and Ser540) are indicated with asterisks.