AI Article Synopsis
- The study investigates the inactivation mechanisms of MEK1 and MEK2, focusing on the role of phosphorylation, specifically at Ser(212), a conserved site among MAPKK family members.
- Mutating Ser(212) to alanine increased MEK1 activity, while mimicking phosphorylation with aspartate blocked activation in both MEK1 and a constitutively active mutant.
- This phosphorylation at Ser(212) does not affect other activation sites and is also functionally significant in yeast MAPKKs, indicating a conserved negative regulatory mechanism across species.
Article Abstract
The MAPKKs MEK1 and MEK2 are activated by phosphorylation, but little is known about how these enzymes are inactivated. Here, we show that MEK1 is phosphorylated in vivo at Ser(212), a residue conserved among all MAPKK family members. Mutation of Ser(212) to alanine enhanced the basal activity of MEK1, whereas the phosphomimetic aspartate mutation completely suppressed the activation of both wild-type MEK1 and the constitutively activated MEK1(S218D/S222D) mutant. Phosphorylation of Ser(212) did not interfere with activating phosphorylation of MEK1 at Ser(218)/Ser(222) or with binding to ERK2 substrate. Importantly, mimicking phosphorylation of the equivalent Ser(212) residue of the yeast MAPKKs Pbs2p and Ste7p similarly abrogated their biological function. Our findings suggest that Ser(212) phosphorylation represents an evolutionarily conserved mechanism involved in the negative regulation of MAPKKs.
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| http://dx.doi.org/10.1074/jbc.M211870200 | DOI Listing |
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