Fig. 1.

Overview of the MAPK/MKP3 signaling network and application of caged cysteine toward caging the catalytic site of the phosphatase. a Schematic of the Ras/Raf/ERK signaling pathway with the dual-specificity phosphatase MKP3 indicated in grey. Upon activation of the pathway by external stimuli, a cascade of phosphorylation events results in dually-phosphorylated ERK, which translocates to the nucleus where it activates additional downstream targets. In the presence of active MKP3, pERK is rapidly dephosphorylated and remains in the cytoplasm. Phosphates are indicated by grey filled circles. b Irradiation of NVC removes the nitrobenzyl caging group (green) and restores a native cysteine residue. c The mechanism of MKP3-catalyzed ERK dephosphorylation. Dashed lines indicate electrostatic and/or hydrogen-bond interactions. d The crystal structure of MKP3 (PDB: 1MKP) is shown with the three critical active site residues labeled in black. On the left, the catalytic cysteine was replaced with NVC, which sterically blocks the active site and prevents catalysis, until exposed to 365 nm light