fig5
Figure 5. GSK-3β phosphorylates Ulk1. (A) Coomassie brilliant blue (CBB) staining and autoradiography after in vitro kinase assay using active recombinant GSK-3β as a kinase and GST-Ulk1K46R, a kinase inactive mutant of human Ulk1, as a substrate. (B) Mass spectrum showing the phosphorylation site (Ser912) in the human Ulk1 sequence. (C) Phosphorylation of Ulk1 at Ser913 in young (Y) and old (O) wild type mice. An immunoblot of GAPDH is shown as an internal control. The bar graph shows the relative band density of pUlk1/Ulk1. The pUlk1/Ulk1 ratio in young mice was designated as 1. *P < 0.05 vs. young.
