MAP2K3 (MKK3, MEK3) is a dual-specificity protein kinase of the STE group that forms the MAP kinase kinase tier of the p38 stress-activated MAPK cascade. It is activated by cytokines and environmental stresses (osmotic, oxidative, inflammatory) through phosphorylation of Ser218 and Thr222 in its activation loop by MAP3Ks such as ASK1 (MAP3K5), TAK1, TAO2 and ZAK, which it binds through docking motifs. Activated MKK3 phosphorylates the threonine and tyrosine of the Thr-Gly-Tyr activation motif of p38 MAP kinases (notably p38alpha/MAPK14 and p38beta), and is selective for p38 over ERK and JNK. It is a soluble protein found in cytoplasm and nucleus and partly redundant with MKK6. Through p38 it contributes to inflammatory, stress-response, endothelial migration and senescence programs. It is a target of bacterial virulence factors (anthrax lethal factor cleavage, Yersinia YopJ acetylation).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000165 MAPK cascade | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference that MAP2K3 participates in a MAPK cascade, from the PANTHER MAP2K family node. Reason: MKK3 is the MAP2K tier of the p38 MAPK cascade. The IBA is placed at a node covering MAP2Ks across eukaryotes and MAP2K3 lies within that clade with direct experimental support (it appears in its own WITH/FROM list). The general term is correct; the more specific p38MAPK cascade (GO:0038066) is separately annotated. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt protein kinase family. MAP kinase kinase subfamily. PMID:8622669 Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. |
| GO:0002931 response to ischemia | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Ensembl Compara projection from rat Map2k3 of response to ischemia. Reason: Ischemia/hypoxia is among the stresses that engage the MKK3-p38 pathway, and the projection comes from an experimentally annotated rat ortholog. It is a physiological context of the p38 cascade rather than a core function of MKK3, so it is retained as non-core. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md Established inputs include oxidative stress, UV irradiation, hypoxia, ischemia, physical or chemical stress, and inflammatory cytokines such as **IL-1 and TNF-Ξ±**. file:human/MAP2K3/MAP2K3-deep-research-falcon.md These are pathway outcomes rather than independent catalytic activities of MKK3. |
| GO:0004672 protein kinase activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro-based assignment of generic protein kinase activity from the Ser/Thr kinase active-site signature. Reason: Correct but uninformative: MKK3 is a dual-specificity MAP kinase kinase whose established substrates are p38 MAPKs. MAP kinase kinase activity (GO:0004708) specifies the conserved substrate class, as in the MAP2K2 review. Proposed replacements: MAP kinase kinase activity Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt Dual specificity kinase. Is activated by cytokines and file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0004708 MAP kinase kinase activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic inference of MAP kinase kinase activity from the PANTHER MAP2K family node. Reason: MAP kinase kinase activity is the defining, conserved function of the MAP2K subfamily and is directly demonstrated for human MKK3 (PMID:8622669). MAP2K3 appears among the node's experimental sources, which indicates the function is inherited rather than lineage-specific. Core function. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt protein kinase family. MAP kinase kinase subfamily. file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0004708 MAP kinase kinase activity | IDA PMID:8622669 MKK3- and MKK6-regulated gene expression is mediated by the ... | ACCEPT | Summary: Raingeaud et al. showed that activated MKK3 selectively activates p38 MAPK in cells, with dual phosphorylation of Ser218/Thr222 controlling MKK3 activity. Reason: Direct experimental evidence for the core function: MKK3 phosphorylates and activates p38 MAPK, and activation-loop mutants of MKK3 are inactive (S/T->A) or constitutively active (S/T->E). Supporting Evidence: PMID:8622669 Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. file:human/MAP2K3/MAP2K3-uniprot.txt Activated by dual phosphorylation on Ser-218 and file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0004708 MAP kinase kinase activity | IEA GO_REF:0000120 | ACCEPT | Summary: Combined automated assignment (ARBA, mouse ortholog, EC 2.7.12.2) of MAP kinase kinase activity. Reason: Consistent with the experimental evidence for MKK3 as a p38-directed MAP2K. Core function. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. file:human/MAP2K3/MAP2K3-deep-research-falcon.md The strongest conclusion is that MKK3 is selective at the MAPK-family level for **p38 MAPKs**, rather than ERK1/2 or JNK. |
| GO:0004708 MAP kinase kinase activity | TAS PMID:7839144 Independent human MAP-kinase signal transduction pathways de... | ACCEPT | Summary: Derijard et al. cloned human MKK3 and showed that it phosphorylates and activates p38 MAP kinase but not ERK. Reason: The founding characterization of MKK3 as a p38-activating MAP kinase kinase. Core function. Supporting Evidence: PMID:7839144 Two human MAP kinase kinases (MKK3 and MKK4) were cloned that phosphorylate and activate p38 MAP kinase. |
| GO:0004708 MAP kinase kinase activity | TAS Reactome:R-HSA-3238999 | ACCEPT | Summary: Reactome reaction in which activated MKK3/MKK6 phosphorylates p38alpha/beta complexed with MAPKAPK5. Reason: Accurately describes MKK3 phosphorylating p38 MAPKs; MAP kinase kinase activity is the core function. Supporting Evidence: Reactome:R-HSA-3238999 Phosphorylation of p38 alpha and p38 beta by MKK3 or MKK6 (Raingeaud et al. 1996), however, is required for the subsequent activation of MAPKAPK5 by p38 MAPK |
| GO:0004708 MAP kinase kinase activity | TAS Reactome:R-HSA-450333 | ACCEPT | Summary: Reactome reaction in which activated MKK3/MKK6 phosphorylates p38 MAPKs complexed with MAPKAPK2 or MAPKAPK3 on the TGY motif. Reason: Accurately describes the core MAP2K reaction of MKK3. Supporting Evidence: Reactome:R-HSA-450333 All of those isoforms are activated by phosphorylation of the Thr and Tyr in the Thr-Gly-Tyr motif in their activation loops. Reactome:R-HSA-450346 both phosphorylate and activate p38 MAP kinase at its activation site Thr-Gly-Tyr but do not phosphorylate or activate Erk1/2 or SAPK/JNK. |
| GO:0004713 protein tyrosine kinase activity | EXP PMID:8622669 MKK3- and MKK6-regulated gene expression is mediated by the ... | MODIFY | Summary: UniProt Rhea-derived assignment of protein tyrosine kinase activity (tyrosine reaction of EC 2.7.12.2) citing PMID:8622669. Reason: MKK3 does phosphorylate a tyrosine (Tyr182 of the p38 TGY motif), but only as part of dual Thr/Tyr phosphorylation of MAP kinases; it is not a general tyrosine kinase. MAP kinase kinase activity (GO:0004708) describes the dual-specificity reaction more informatively, as in the MAP2K2 review. Proposed replacements: MAP kinase kinase activity Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. PMID:8622669 Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. |
| GO:0004713 protein tyrosine kinase activity | IEA GO_REF:0000116 | MODIFY | Summary: Rhea-mapping IEA of protein tyrosine kinase activity (RHEA:10596). Reason: As for the EXP row: the tyrosine phosphorylation is the Tyr of the p38 TGY activation motif within a dual-specificity MAP2K reaction, better captured by MAP kinase kinase activity (GO:0004708). Proposed replacements: MAP kinase kinase activity Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt Reaction=L-tyrosyl-[protein] + ATP = O-phospho-L-tyrosyl-[protein] + file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0005515 protein binding | IPI PMID:11980910 Mirk protein kinase is activated by MKK3 and functions as a ... | MODIFY | Summary: Lim et al. showed that Mirk/DYRK1B co-immunoprecipitates with MKK3 and that MKK3 enhances Mirk kinase activity. Reason: Bare protein binding is uninformative. The partner DYRK1B is a protein kinase whose activity is increased by MKK3, so protein kinase binding (GO:0019901) is the informative replacement. Whether MKK3 directly phosphorylates DYRK1B is not established in the available abstract, so a MAPKK-specific term is not proposed. Proposed replacements: protein kinase binding Supporting Evidence: PMID:11980910 Mirk co-immunoprecipitated with the MAPK kinase MKK3, an upstream activator of p38. MKK3 enhanced Mirk kinase activity file:human/MAP2K3/MAP2K3-uniprot.txt Binds to DYRK1B/MIRK and increases its kinase |
| GO:0005515 protein binding | IPI PMID:17255949 Mxi2 promotes stimulus-independent ERK nuclear translocation... | MODIFY | Summary: IPI for MAP2K3 binding MAPK14 (p38alpha), its principal physiological substrate (PMID:17255949). Reason: Bare protein binding is uninformative. The partner p38alpha (MAPK14) is the MAP kinase that MKK3 docks onto and dually phosphorylates on its TGY activation loop; the interaction is reproduced in multiple independent studies (UniProt/IntAct NbExp=7). Mitogen-activated protein kinase binding (GO:0051019) captures the informative, substrate-recognition aspect of this interaction. Proposed replacements: mitogen-activated protein kinase binding Supporting Evidence: PMID:17255949 Mxi2 is capable of interacting with MKK 3 and 6 file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q16539: MAPK14; NbExp=7; IntAct=EBI-602462, EBI-73946; file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0005515 protein binding | IPI PMID:19805025 CIB1 functions as a Ca(2+)-sensitive modulator of stress-ind... | MODIFY | Summary: IPI for MAP2K3 binding MAP3K5 (ASK1), an upstream MAP kinase kinase kinase that phosphorylates and activates MKK3 (PMID:19805025). Reason: Bare protein binding is uninformative. ASK1/MAP3K5 is an established upstream MAP3K for MKK3, and binding is mediated by the C-terminal DVD docking site of MKK3 that is required for ASK1-mediated activation. Mitogen-activated protein kinase kinase kinase binding (GO:0031435) is the informative replacement, consistent with the term choice in the MAP2K2 review. Proposed replacements: mitogen-activated protein kinase kinase kinase binding Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q99683: MAP3K5; NbExp=6; IntAct=EBI-602462, EBI-476263; Reactome:R-HSA-3228469 A conserved docking site, DVD, at the C-terminus of MAP2K3 and MAP2K6 is needed for the interaction with MAP3K5 and MAP3K5-mediated activation |
| GO:0005515 protein binding | IPI PMID:20067578 MKK6 binds and regulates expression of Parkinson's disease-r... | MODIFY | Summary: IPI for MAP2K3 binding LRRK2, a kinase reported to bind and phosphorylate MKK3, MKK6 and MKK7 (PMID:20067578). Reason: Bare protein binding is uninformative. LRRK2 is a protein kinase that binds MKK3 and can phosphorylate it (PMID:20067578), so protein kinase binding (GO:0019901) is the informative replacement. The physiological significance of LRRK2 as an MKK3 activator is less established than for canonical MAP3Ks, so the more specific MAPKKK binding term is not proposed. Proposed replacements: protein kinase binding Supporting Evidence: PMID:20067578 we show that LRRK2 binds to MAPK kinases (MKK) 3, 6, and 7, and that LRRK2 is able to phosphorylate MKK3, 6 and 7. file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q5S007: LRRK2; NbExp=5; IntAct=EBI-602462, EBI-5323863; |
| GO:0005515 protein binding | IPI PMID:20173330 LRRK2 and the stress response: interaction with MKKs and JNK... | MODIFY | Summary: IPI for MAP2K3 binding LRRK2, a kinase reported to bind and phosphorylate MKK3, MKK6 and MKK7 (PMID:20173330). Reason: Bare protein binding is uninformative. LRRK2 is a protein kinase that binds MKK3 and can phosphorylate it (PMID:20067578), so protein kinase binding (GO:0019901) is the informative replacement. The physiological significance of LRRK2 as an MKK3 activator is less established than for canonical MAP3Ks, so the more specific MAPKKK binding term is not proposed. Proposed replacements: protein kinase binding Supporting Evidence: PMID:20067578 we show that LRRK2 binds to MAPK kinases (MKK) 3, 6, and 7, and that LRRK2 is able to phosphorylate MKK3, 6 and 7. file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q5S007: LRRK2; NbExp=5; IntAct=EBI-602462, EBI-5323863; |
| GO:0005515 protein binding | IPI PMID:21044950 Genome-wide YFP fluorescence complementation screen identifi... | REMOVE | Summary: Interaction of MAP2K3 with TINF2 (TIN2) detected in a genome-wide YFP fluorescence complementation screen for telomere-protein interactors. Reason: Bare protein binding is uninformative, and this screen-derived interaction has no functional follow-up for MKK3 that would support a more specific molecular function term. Removal does not imply the interaction is false; it only reflects that the generic term adds no functional information. Supporting Evidence: PMID:21044950 Of the βΌ12,000 human proteins examined, we identified over 300 proteins that associated with the six core telomeric proteins. file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q9BSI4: TINF2; NbExp=2; IntAct=EBI-602462, EBI-717399; |
| GO:0005515 protein binding | IPI PMID:21771788 Positive regulation of apoptosis signal-regulating kinase 1 ... | MODIFY | Summary: IPI for MAP2K3 binding MAP3K5 (ASK1), an upstream MAP kinase kinase kinase that phosphorylates and activates MKK3 (PMID:21771788). Reason: Bare protein binding is uninformative. ASK1/MAP3K5 is an established upstream MAP3K for MKK3, and binding is mediated by the C-terminal DVD docking site of MKK3 that is required for ASK1-mediated activation. Mitogen-activated protein kinase kinase kinase binding (GO:0031435) is the informative replacement, consistent with the term choice in the MAP2K2 review. Proposed replacements: mitogen-activated protein kinase kinase kinase binding Supporting Evidence: PMID:21771788 increasing complex formation between ASK1 and its substrate MKK3 file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q99683: MAP3K5; NbExp=6; IntAct=EBI-602462, EBI-476263; Reactome:R-HSA-3228469 A conserved docking site, DVD, at the C-terminus of MAP2K3 and MAP2K6 is needed for the interaction with MAP3K5 and MAP3K5-mediated activation |
| GO:0005515 protein binding | IPI PMID:23602568 The protein interaction landscape of the human CMGC kinase g... | MODIFY | Summary: IPI for MAP2K3 binding MAPK14 (p38alpha), its principal physiological substrate (PMID:23602568). Reason: Bare protein binding is uninformative. The partner p38alpha (MAPK14) is the MAP kinase that MKK3 docks onto and dually phosphorylates on its TGY activation loop; the interaction is reproduced in multiple independent studies (UniProt/IntAct NbExp=7). Mitogen-activated protein kinase binding (GO:0051019) captures the informative, substrate-recognition aspect of this interaction. Proposed replacements: mitogen-activated protein kinase binding Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q16539: MAPK14; NbExp=7; IntAct=EBI-602462, EBI-73946; file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0005515 protein binding | IPI PMID:31980649 Extensive rewiring of the EGFR network in colorectal cancer ... | MODIFY | Summary: IPI for MAP2K3 binding MAPK14 (p38alpha), its principal physiological substrate (PMID:31980649). Reason: Bare protein binding is uninformative. The partner p38alpha (MAPK14) is the MAP kinase that MKK3 docks onto and dually phosphorylates on its TGY activation loop; the interaction is reproduced in multiple independent studies (UniProt/IntAct NbExp=7). Mitogen-activated protein kinase binding (GO:0051019) captures the informative, substrate-recognition aspect of this interaction. Proposed replacements: mitogen-activated protein kinase binding Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q16539: MAPK14; NbExp=7; IntAct=EBI-602462, EBI-73946; file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0005515 protein binding | IPI PMID:31980649 Extensive rewiring of the EGFR network in colorectal cancer ... | MODIFY | Summary: IPI for MAP2K3 binding MAP3K5 (ASK1), an upstream MAP kinase kinase kinase that phosphorylates and activates MKK3 (PMID:31980649). Reason: Bare protein binding is uninformative. ASK1/MAP3K5 is an established upstream MAP3K for MKK3, and binding is mediated by the C-terminal DVD docking site of MKK3 that is required for ASK1-mediated activation. Mitogen-activated protein kinase kinase kinase binding (GO:0031435) is the informative replacement, consistent with the term choice in the MAP2K2 review. Proposed replacements: mitogen-activated protein kinase kinase kinase binding Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q99683: MAP3K5; NbExp=6; IntAct=EBI-602462, EBI-476263; Reactome:R-HSA-3228469 A conserved docking site, DVD, at the C-terminus of MAP2K3 and MAP2K6 is needed for the interaction with MAP3K5 and MAP3K5-mediated activation |
| GO:0005515 protein binding | IPI PMID:32707033 Kinase Interaction Network Expands Functional and Disease Ro... | MODIFY | Summary: IPI for MAP2K3 binding MAPK14 (p38alpha), its principal physiological substrate (PMID:32707033). Reason: Bare protein binding is uninformative. The partner p38alpha (MAPK14) is the MAP kinase that MKK3 docks onto and dually phosphorylates on its TGY activation loop; the interaction is reproduced in multiple independent studies (UniProt/IntAct NbExp=7). Mitogen-activated protein kinase binding (GO:0051019) captures the informative, substrate-recognition aspect of this interaction. Proposed replacements: mitogen-activated protein kinase binding Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q16539: MAPK14; NbExp=7; IntAct=EBI-602462, EBI-73946; file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | MODIFY | Summary: IPI for MAP2K3 binding MAPK14 (p38alpha), its principal physiological substrate (PMID:33961781). Reason: Bare protein binding is uninformative. The partner p38alpha (MAPK14) is the MAP kinase that MKK3 docks onto and dually phosphorylates on its TGY activation loop; the interaction is reproduced in multiple independent studies (UniProt/IntAct NbExp=7). Mitogen-activated protein kinase binding (GO:0051019) captures the informative, substrate-recognition aspect of this interaction. Proposed replacements: mitogen-activated protein kinase binding Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q16539: MAPK14; NbExp=7; IntAct=EBI-602462, EBI-73946; file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:0005524 ATP binding | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro-based assignment of ATP binding from the protein kinase domain. Reason: ATP is the phosphate donor for the MKK3-catalysed phosphorylation of p38; the kinase domain contains the canonical ATP-binding residues (70-78, Lys93). Correct supporting function. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt Reaction=L-tyrosyl-[protein] + ATP = O-phospho-L-tyrosyl-[protein] + |
| GO:0005654 nucleoplasm | TAS Reactome:R-HSA-3238999 | ACCEPT | Summary: Reactome places activated MKK3 in the nucleoplasm, where it phosphorylates nuclear p38 (Reactome:R-HSA-3238999). Reason: MKK3 is present in both nucleus and cytoplasm, consistent with a role in activating nuclear p38. Acceptable location annotation. Supporting Evidence: Reactome:R-HSA-450296 The p38 activators MKK3 (MAP2K3) and MKK6 (MAP2K6) were present in both the nucleus and the cytoplasm, consistent with a role in activating p38 in the nucleus. file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. |
| GO:0005654 nucleoplasm | TAS Reactome:R-HSA-450296 | ACCEPT | Summary: Reactome places activated MKK3 in the nucleoplasm, where it phosphorylates nuclear p38 (Reactome:R-HSA-450296). Reason: MKK3 is present in both nucleus and cytoplasm, consistent with a role in activating nuclear p38. Acceptable location annotation. Supporting Evidence: Reactome:R-HSA-450296 The p38 activators MKK3 (MAP2K3) and MKK6 (MAP2K6) were present in both the nucleus and the cytoplasm, consistent with a role in activating p38 in the nucleus. file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. |
| GO:0005654 nucleoplasm | TAS Reactome:R-HSA-450333 | ACCEPT | Summary: Reactome places activated MKK3 in the nucleoplasm, where it phosphorylates nuclear p38 (Reactome:R-HSA-450333). Reason: MKK3 is present in both nucleus and cytoplasm, consistent with a role in activating nuclear p38. Acceptable location annotation. Supporting Evidence: Reactome:R-HSA-450296 The p38 activators MKK3 (MAP2K3) and MKK6 (MAP2K6) were present in both the nucleus and the cytoplasm, consistent with a role in activating p38 in the nucleus. file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. |
| GO:0005737 cytoplasm | TAS PMID:8622669 MKK3- and MKK6-regulated gene expression is mediated by the ... | ACCEPT | Summary: Traceable author statement that MKK3 acts in the cytoplasm (PMID:8622669). Reason: MKK3 is a soluble intracellular kinase detected in cytoplasm (and nucleus); cytoplasm is where it is engaged by MAP3K signalling complexes. Accept. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. Reactome:R-HSA-450296 The p38 activators MKK3 (MAP2K3) and MKK6 (MAP2K6) were present in both the nucleus and the cytoplasm, consistent with a role in activating p38 in the nucleus. |
| GO:0005829 cytosol | TAS Reactome:R-HSA-3228469 | ACCEPT | Summary: Reactome places MKK3 in the cytosol, where it is phosphorylated by MAP3Ks (ASK1, TAK1) or cleaved by anthrax lethal factor (Reactome:R-HSA-3228469). Reason: MKK3 is a soluble cytoplasmic kinase that is activated by cytosolic MAP3Ks. Accept. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. Reactome:R-HSA-3228469 MAP3K5 (ASK1) phosphorylates and activates MAP2K3 (MKK3) and MAP2K6 (MKK6) |
| GO:0005829 cytosol | TAS Reactome:R-HSA-450296 | ACCEPT | Summary: Reactome places MKK3 in the cytosol, where it is phosphorylated by MAP3Ks (ASK1, TAK1) or cleaved by anthrax lethal factor (Reactome:R-HSA-450296). Reason: MKK3 is a soluble cytoplasmic kinase that is activated by cytosolic MAP3Ks. Accept. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. Reactome:R-HSA-3228469 MAP3K5 (ASK1) phosphorylates and activates MAP2K3 (MKK3) and MAP2K6 (MKK6) |
| GO:0005829 cytosol | TAS Reactome:R-HSA-450346 | ACCEPT | Summary: Reactome places MKK3 in the cytosol, where it is phosphorylated by MAP3Ks (ASK1, TAK1) or cleaved by anthrax lethal factor (Reactome:R-HSA-450346). Reason: MKK3 is a soluble cytoplasmic kinase that is activated by cytosolic MAP3Ks. Accept. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. Reactome:R-HSA-3228469 MAP3K5 (ASK1) phosphorylates and activates MAP2K3 (MKK3) and MAP2K6 (MKK6) |
| GO:0005829 cytosol | TAS Reactome:R-HSA-5211400 | ACCEPT | Summary: Reactome places MKK3 in the cytosol, where it is phosphorylated by MAP3Ks (ASK1, TAK1) or cleaved by anthrax lethal factor (Reactome:R-HSA-5211400). Reason: MKK3 is a soluble cytoplasmic kinase that is activated by cytosolic MAP3Ks. Accept. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md MAP2K3 is a soluble intracellular kinase and has been detected in **both cytoplasm and nucleus**. Reactome:R-HSA-3228469 MAP3K5 (ASK1) phosphorylates and activates MAP2K3 (MKK3) and MAP2K6 (MKK6) |
| GO:0007165 signal transduction | TAS PMID:7839144 Independent human MAP-kinase signal transduction pathways de... | MODIFY | Summary: Traceable author statement that MKK3 functions in signal transduction (PMID:7839144). Reason: Correct but too general. The paper defines MKK3 as an activator of p38 in a MAP kinase pathway distinct from ERK, so the specific process is the p38MAPK cascade (GO:0038066). Proposed replacements: p38MAPK cascade Supporting Evidence: PMID:7839144 Two human MAP kinase kinases (MKK3 and MKK4) were cloned that phosphorylate and activate p38 MAP kinase. PMID:7839144 These data demonstrate that the activators of p38 (MKK3 and MKK4), JNK (MKK4), and ERK (MEK1 and MEK2) define independent MAP kinase signal transduction pathways. |
| GO:0007507 heart development | IEA GO_REF:0000107 | MARK AS OVER ANNOTATED | Summary: Ensembl Compara projection from rat Map2k3 of heart development. Reason: There is no evidence in the reviewed literature that MKK3 performs a heart-developmental function as opposed to acting generically in p38 stress signalling, and MKK3 is largely redundant with MKK6. A developmental phenotype-derived process projected from a rodent ortholog is an over-annotation for the human protein. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md These are pathway outcomes rather than independent catalytic activities of MKK3. |
| GO:0016020 membrane | HDA PMID:19946888 Defining the membrane proteome of NK cells. | KEEP AS NON CORE | Summary: MAP2K3 was identified in a mass-spectrometry survey of the membrane proteome of YTS NK-like cells. Reason: MKK3 is a soluble kinase without transmembrane segments; detection in membrane fractions likely reflects transient association with membrane signalling complexes (e.g. ARRB1-dependent plasma-membrane p38 signalosomes reported in UniProt). Retained as a non-core high-throughput localization. Supporting Evidence: PMID:19946888 The remaining species were largely involved in cellular processes and molecular functions that could be predicted to be transiently associated with membranes. file:human/MAP2K3/MAP2K3-uniprot.txt CCM2 (By similarity). Interacts with ARRB1 (PubMed:16709866). |
| GO:0019901 protein kinase binding | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Combined automated assignment (ARBA, mouse ortholog) of protein kinase binding. Reason: MKK3 binds upstream MAP3Ks (ASK1, TAO2, TAK1, ZAK) and its substrate p38 MAPKs, so protein kinase binding is correct; it is a consequence of the core MAPKK activity rather than a separate function. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q16539: MAPK14; NbExp=7; IntAct=EBI-602462, EBI-73946; file:human/MAP2K3/MAP2K3-uniprot.txt P46734; Q99683: MAP3K5; NbExp=6; IntAct=EBI-602462, EBI-476263; file:human/MAP2K3/MAP2K3-uniprot.txt (PubMed:21224381). Binds to DYRK1B/MIRK and increases its kinase |
| GO:0019901 protein kinase binding | IPI PMID:11279118 Regulation of stress-responsive mitogen-activated protein (M... | KEEP AS NON CORE | Summary: Chen and Cobb showed that endogenous TAO2 (TAOK2) specifically co-immunoprecipitates with MEK3 and MEK6 and activates them toward p38. Reason: Correct and experimentally supported: TAO2 acts as a MAP kinase kinase kinase for MKK3/MKK6, so binding it is part of how MKK3 is recruited and activated. Kept as non-core supporting binding (consistent with the IEA row for the same term); the more specific mitogen-activated protein kinase kinase kinase binding (GO:0031435) is proposed via the MAP3K5 protein-binding rows. Supporting Evidence: PMID:11279118 Coimmunoprecipitation demonstrated that endogenous TAO2 specifically associates with MEK3 and MEK6 providing one mechanism for preferential recognition of MEKs upstream of p38. file:human/MAP2K3/MAP2K3-uniprot.txt Phosphorylated by TAOK2 (PubMed:11279118). |
| GO:0031098 stress-activated protein kinase signaling cascade | IDA PMID:8622669 MKK3- and MKK6-regulated gene expression is mediated by the ... | ACCEPT | Summary: Raingeaud et al. showed that activated MKK3 selectively activates the stress- and cytokine-responsive p38 MAPK. Reason: The p38 cascade is a stress-activated MAPK cascade and MKK3 is its MAP2K tier. Accept; the more specific p38MAPK cascade (GO:0038066) is also annotated. Supporting Evidence: PMID:8622669 Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. file:human/MAP2K3/MAP2K3-uniprot.txt Dual specificity kinase. Is activated by cytokines and |
| GO:0031098 stress-activated protein kinase signaling cascade | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA machine-learning assignment of stress-activated protein kinase signaling cascade. Reason: Consistent with experimental evidence placing MKK3 in the stress-activated p38 cascade. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt Dual specificity kinase. Is activated by cytokines and Reactome:R-HSA-450346 both phosphorylate and activate p38 MAP kinase at its activation site Thr-Gly-Tyr but do not phosphorylate or activate Erk1/2 or SAPK/JNK. |
| GO:0035331 negative regulation of hippo signaling | IMP PMID:27402810 Regulation of Hippo signalling by p38 signalling. | KEEP AS NON CORE | Summary: Huang et al. found that the Drosophila p38 pathway (via the MKK3/6 homologue Licorne) inhibits Hippo signalling, and that human MKK3 promotes YAP nuclear localization via F-actin accumulation. Reason: The effect of MKK3 on Hippo/YAP output is indirect, acting through p38 signalling and F-actin assembly, and was shown in mammalian cells mainly by MKK3 overexpression. It is a downstream context of MKK3-p38 signalling rather than a core function, but the curator's interpretation is plausible, so it is retained as non-core. Supporting Evidence: PMID:27402810 The Lic homologue MKK3 promoted nuclear localization of YAP by inducing F-actin accumulation. PMID:27402810 Transfected MKK3 strongly enhanced YAP1-mediated reporter expression. |
| GO:0035924 cellular response to vascular endothelial growth factor stimulus | IMP PMID:22696064 miR-20a represses endothelial cell migration by targeting MK... | KEEP AS NON CORE | Summary: Pin et al. showed that siRNA knockdown of MKK3 impairs VEGF-induced p38 activation and endothelial cell migration. Reason: MKK3 is required to relay VEGFR2 signalling to p38 in endothelial cells. This is a cell-type specific context of the core MKK3-p38 function; retained as non-core. Supporting Evidence: PMID:22696064 the VEGF-induced activation of p38 and cell migration are impaired when the MKK3 expression is knocked down by siRNA. |
| GO:0038066 p38MAPK cascade | IEA GO_REF:0000117 | ACCEPT | Summary: ARBA machine-learning assignment of p38MAPK cascade. Reason: MKK3 is the MAP2K tier of the p38 cascade. Core process. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. file:human/MAP2K3/MAP2K3-deep-research-falcon.md The strongest conclusion is that MKK3 is selective at the MAPK-family level for **p38 MAPKs**, rather than ERK1/2 or JNK. |
| GO:0038066 p38MAPK cascade | IMP PMID:22696064 miR-20a represses endothelial cell migration by targeting MK... | ACCEPT | Summary: MKK3 knockdown impairs VEGF-induced p38 activation in endothelial cells (PMID:22696064). Reason: Loss-of-function evidence that MKK3 is required for p38 activation; MKK3 directly phosphorylates p38, so it performs a step of the cascade. Core process. Supporting Evidence: PMID:22696064 the VEGF-induced activation of p38 and cell migration are impaired when the MKK3 expression is knocked down by siRNA. |
| GO:0038066 p38MAPK cascade | TAS Reactome:R-HSA-450302 | ACCEPT | Summary: Reactome pathway in which TAK1 phosphorylates MKK3/4/6, which in turn activate p38 MAPK. Reason: MKK3 is a direct kinase step in the p38 cascade. Core process. Supporting Evidence: Reactome:R-HSA-450302 Each isoform is activated by upstream kinases including MAP kinase kinases (MKK) 3, 4, and 6, which in turn are phosphorylated by activated TAK1 |
| GO:0043536 positive regulation of blood vessel endothelial cell migration | IMP PMID:22696064 miR-20a represses endothelial cell migration by targeting MK... | KEEP AS NON CORE | Summary: MKK3 knockdown impairs VEGF-induced endothelial cell migration (PMID:22696064). Reason: MKK3 contributes to VEGF-induced endothelial migration through p38 activation. This is a downstream physiological outcome of the core function; retained as non-core. Supporting Evidence: PMID:22696064 the VEGF-induced activation of p38 and cell migration are impaired when the MKK3 expression is knocked down by siRNA. PMID:22696064 Endothelial cell migration induced in response to vascular endothelial growth factor (VEGF) is a crucial step of angiogenesis and it depends on the activation of the p38 MAP-kinase pathway downstream of VEGFR2. |
| GO:0045860 positive regulation of protein kinase activity | IDA PMID:11980910 Mirk protein kinase is activated by MKK3 and functions as a ... | KEEP AS NON CORE | Summary: MKK3 enhanced the kinase activity of Mirk/DYRK1B (PMID:11980910). Reason: Supported by the cited experiment; MKK3 also activates p38 kinases as its core function, which is better captured by MAP kinase kinase activity. The DYRK1B effect is a secondary, less-characterized activity; retained as non-core. Supporting Evidence: PMID:11980910 MKK3 enhanced Mirk kinase activity and the transcriptional activation of HNF1alpha by Mirk file:human/MAP2K3/MAP2K3-uniprot.txt Binds to DYRK1B/MIRK and increases its kinase |
| GO:0045893 positive regulation of DNA-templated transcription | IDA PMID:11980910 Mirk protein kinase is activated by MKK3 and functions as a ... | MARK AS OVER ANNOTATED | Summary: MKK3 enhanced HNF1alpha transcriptional activation by Mirk/DYRK1B in reporter assays (PMID:11980910). Reason: MKK3 is a cytoplasmic/nuclear protein kinase with no transcription-regulatory activity of its own; the reporter effect is indirect, via activation of Mirk, which acts on HNF1alpha. Downstream transcriptional outputs of kinase cascades are over-annotations for the upstream MAP2K. Supporting Evidence: PMID:11980910 Mirk may function as an HNF1alpha transcriptional activator in response to an MKK3-mediated stress signal file:human/MAP2K3/MAP2K3-deep-research-falcon.md These are pathway outcomes rather than independent catalytic activities of MKK3. |
| GO:0071222 cellular response to lipopolysaccharide | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Ensembl Compara projection from rat Map2k3 of cellular response to lipopolysaccharide. Reason: The MKK3-p38 pathway is activated by inflammatory stimuli and contributes to innate immune signalling; LPS response is a physiological context, not a core function. Retained as non-core. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md inflammatory cytokine production and innate-immune signaling; file:human/MAP2K3/MAP2K3-deep-research-falcon.md These are pathway outcomes rather than independent catalytic activities of MKK3. |
| GO:0072709 cellular response to sorbitol | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Ensembl Compara projection from rat Map2k3 of cellular response to sorbitol. Reason: Hyperosmotic sorbitol activates the MAP3K TAO2 toward MEK3/MEK6 and hence p38 (PMID:11279118). Reasonable stress context of MKK3 signalling; retained as non-core. Supporting Evidence: PMID:11279118 Sorbitol, and to a lesser extent, sodium chloride, Taxol, and nocodazole increased TAO2 activity toward itself and kinase-dead MEKs 3 and 6. |
| GO:0090398 cellular senescence | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: ARBA machine-learning assignment of cellular senescence. Reason: p38 signalling downstream of MKK3/MKK6 contributes to oxidative-stress- and oncogene-induced senescence; this is a downstream outcome of the p38 cascade rather than a core function of MKK3. Supporting Evidence: file:human/MAP2K3/MAP2K3-deep-research-falcon.md cell-cycle arrest, survival or apoptosis, depending on context; file:human/MAP2K3/MAP2K3-deep-research-falcon.md These are pathway outcomes rather than independent catalytic activities of MKK3. |
| GO:0090398 cellular senescence | TAS Reactome:R-HSA-2559583 | KEEP AS NON CORE | Summary: Reactome Cellular Senescence pathway, which includes MKK3/MKK6-mediated p38 activation in oxidative-stress-induced senescence. Reason: Membership in the senescence pathway reflects the p38 stress branch; MKK3 contributes as the p38-activating kinase. Retained as a non-core process. Supporting Evidence: Reactome:R-HSA-2559583 Oxidative stress, which may or may not be caused by oncogenic RAS signaling, can also trigger senescence. |
| GO:0106310 protein serine kinase activity | EXP PMID:8622669 MKK3- and MKK6-regulated gene expression is mediated by the ... | MODIFY | Summary: UniProt Rhea-derived assignment of protein serine kinase activity (serine reaction of EC 2.7.12.2) citing PMID:8622669. Reason: The established MKK3 reaction is phosphorylation of Thr and Tyr in the p38 TGY motif; the serine reaction is carried over from the generic EC 2.7.12.2 definition rather than from an identified serine substrate. MAP kinase kinase activity (GO:0004708) is the accurate, informative description, as in the MAP2K2 review. Proposed replacements: MAP kinase kinase activity Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. PMID:8622669 Expression of activated MKK3 and MKK6 in cultured cells caused a selective increase in p38 MAP kinase activity. |
| GO:0106310 protein serine kinase activity | IEA GO_REF:0000116 | MODIFY | Summary: Rhea-mapping IEA of protein serine kinase activity (RHEA:17989). Reason: Generic EC-level mapping; no serine substrate of MKK3 is established. Replace with MAP kinase kinase activity (GO:0004708). Proposed replacements: MAP kinase kinase activity Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. |
| GO:1902531 regulation of intracellular signal transduction | IEA GO_REF:0000117 | MARK AS OVER ANNOTATED | Summary: ARBA machine-learning assignment of regulation of intracellular signal transduction. Reason: MKK3 is a core transducing kinase of the p38 cascade rather than a regulator of signal transduction; its role is captured precisely by p38MAPK cascade (GO:0038066) and MAP kinase kinase activity. This vague regulation term adds no information and over-states a regulatory role. Supporting Evidence: file:human/MAP2K3/MAP2K3-uniprot.txt of a threonine and a tyrosine residue in the MAP kinase p38. file:human/MAP2K3/MAP2K3-deep-research-falcon.md The strongest conclusion is that MKK3 is selective at the MAPK-family level for **p38 MAPKs**, rather than ERK1/2 or JNK. |
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Download this section (compressed HTML)Q: Which p38 isoforms (alpha, beta, gamma, delta) does MKK3 preferentially activate in vivo relative to MKK6, and does this preference differ between the MKK3 splice isoforms?
Q: Does MKK3 directly phosphorylate DYRK1B/Mirk, or does it increase Mirk activity through a non-catalytic or p38-dependent mechanism?
Experiment: In vitro kinase assays with purified active MKK3 and each recombinant p38 isoform (and DYRK1B), combined with phosphosite mapping, to define MKK3 substrate preferences quantitatively.
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