(A) JEG3 cells were cotransfected with a series of expression vectors as described. Flag-tagged SIRT1 proteins were immunoprecipitated by FLAG antibody, and abundance of coimmunoprecipitated proteins was determined by western blotting using anti-Myc antibody (top right panel) and anti-SIRT1 antibody (bottom right panel). Left panels show the immunoblotting results of total cell lysates as an input.
(B and C) SIRT1 and CLOCK interaction in vivo. Endogenous CLOCK:BMAL1 and SIRT1 interactions in the mice liver (B) and in cultured MEFs after serum shock
(C) were determined by coimmunoprecipitation assays.
(D) The deacetylase-deficient (H363Y) mutant SIRT1 interacts with CLOCK as well as WT SIRT1.
(E) CLOCK (aa 450–570) is required for the interaction with SIRT1. In vitro-translated [35S]-labeled truncated CLOCK proteins were pulled down by GST-SIRT1.
(F) SIRT1 N terminus (aa 1–231) is required for CLOCK interaction. In vitro-translated [35S]-labeled full-length CLOCK proteins were pulled down by truncated GST-SIRT1.