Metal‐dependent protein phosphatase 1A functions as an extracellular signal‐regulated kinase phosphatase

Protein phosphorylation is an important post‐translational modification that regulates almost every aspect of signal transduction in cells. Activation of the mitogen‐activated protein kinase ( MAPK ) family kinase extracellular signal‐regulated kinase ( ERK ) is a point of convergence for many cellular activities in response to external stimulation. With stimuli, ERK activity is significantly increased by the phosphorylation of Thr202 and Tyr204 at its activation loop. Downregulation of ERK phosphorylation at these two sites by several phosphatases, such as protein phosphatase 2A, H e PTP and MAPK phosphatase 3, is essential for maintaining appropriate ERK function in different cellular processes. However, it is unknown whether metal‐dependent protein phosphatase ( PPM ) family phosphatases directly dephosphorylate ERK . In this study, we found that PPM 1 A negatively regulated ERK by directly dephosphorylating its pThr202 position early in EGF stimulation. Additional kinetic studies revealed that key residues participated in phospho‐ ERK recognition by PPM 1 A . Importantly, PPM 1 A preferred the phospho‐ ERK peptide sequence over a panel of other phosphopeptides through the interactions of basic residues in the active site of PPM 1 A with the pThr‐Glu‐pTyr motif of ERK . Whereas Lys165 and Arg33 were required for efficient catalysis or phosphosubstrate binding of PPM 1 A , Gln185 and Arg186 were determinants of PPM 1 A substrate specificity. The interaction between Arg186 of PPM 1 A and Glu203 and pTyr204 of phospho‐ ERK was identified as a hot‐spot for phospho‐ ERK – PPM 1 A interaction. Structured digital abstract PPM1A physically interacts with ERK2 by pull down ( View interaction ) PPM1A dephosphorylates p38 by phosphatase assay (View Interaction: 1 , 2 ) PPM1A binds to ERK2 by pull down ( View interaction ) PPM1A dephosphorylates ERK2 by phosphatase assay (View Interaction: 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , <jats:ext-link xmlns:xlink="http://www.w3.org/1999