id: A0A9L0SHX8 gene_symbol: MAP2K2 product_type: PROTEIN status: COMPLETE taxon: id: NCBITaxon:9796 label: Equus caballus description: MAP2K2 (MEK2) is a cytoplasmic dual-specificity protein kinase of the MAP kinase kinase family that acts in the RAF-MEK-ERK cascade. Once activated by RAF phosphorylation of its activation loop, it phosphorylates the threonine and tyrosine of the Thr-Glu-Tyr motif in the activation loop of the ERK1 and ERK2 MAP kinases, relaying growth-factor and mitogen signals to ERK-dependent control of proliferation and differentiation. The horse entry A0A9L0SHX8 is one of several gene-model products of the horse MAP2K2 locus; it retains the N-terminal ERK-docking region and the catalytic core (human residues 1-363) but carries an unrelated 27-residue C-terminal tail in place of the final part of the kinase domain and the C-terminal DVD docking region. existing_annotations: - term: id: GO:0000165 label: MAPK cascade evidence_type: IEA original_reference_id: GO_REF:0000108 qualifier: involved_in supporting_entities: - GO:0004708 review: action: MODIFY summary: MEK2 is an ERK1/ERK2-specific MAP2K; MAPK cascade is correct but less specific than the ERK1 and ERK2 cascade. reason: PAINT node PTN000684494 (eukaryote-level, human P36507 among the seeds) asserts MAPK cascade, and horse MAP2K2 (PANTHER PTHR47448:SF3, MAP2K2 subfamily) descends from it, so the claim holds. Within the MAP2K family, MEK1/MEK2 activate only ERK1/ERK2 (human MEK2 phosphorylates and activates ERK1, PMID:8388392), so the precise process is GO:0070371 ERK1 and ERK2 cascade, an is_a descendant of GO:0000165, which the human MAP2K2 review accepts. A0A9L0SHX8 is an alternative horse MAP2K2 gene model that retains human MEK2 residues 1-363 (Lys101, Asp194, Ser222/Ser226 conserved) but replaces human 364-400, including the DVD docking region, with an unrelated tail; the row is judged as a claim about the horse MAP2K2 gene product, and the activity of this particular splice form is untested. supported_by: - reference_id: file:HORSE/MAP2K2/MAP2K2-bioinformatics/RESULTS-rereview.md supporting_text: 'node PTN000684494 asserts GO:0000165 (P, IBD, negated=false), taxon taxon:2759; 29 seeds; human P36507 among seeds: True' - &id002 reference_id: PMID:8388392 supporting_text: "Both MEK1 \nand MEK2 were expressed in Escherichia coli and shown to be able to activate\ \ \nrecombinant human ERK1 in vitro. The purified MEK2 protein stimulated threonine \nand tyrosine phosphorylation\ \ on ERK1 and concomitantly activated ERK1 kinase \nactivity more than 100-fold." - &id004 reference_id: file:human/MAP2K2/MAP2K2-uniprot.txt record_section: ["CC:FUNCTION"] supporting_text: 'CC -!- FUNCTION: Catalyzes the concomitant phosphorylation of a threonine and CC a tyrosine residue in a Thr-Glu-Tyr sequence located in MAP kinases. CC Activates the ERK1 and ERK2 MAP kinases (By similarity). Activates BRAF CC in a KSR1 or KSR2-dependent manner; by binding to KSR1 or KSR2 releases CC the inhibitory intramolecular interaction between KSR1 or KSR2 protein CC kinase and N-terminal domains which promotes KSR1 or KSR2-BRAF CC dimerization and BRAF activation (PubMed:29433126). CC {ECO:0000250|UniProtKB:Q63932, ECO:0000269|PubMed:29433126}.' - &id001 reference_id: file:HORSE/MAP2K2/MAP2K2-bioinformatics/RESULTS-rereview.md supporting_text: '| A0A9L0SHX8 (target) | 390 | ENSECAT00000136538 | False | 11 | 90.26 | 97.5 | 363 | K D S S L S | 2/8 | 2/31 |' proposed_replacement_terms: - id: GO:0070371 label: ERK1 and ERK2 cascade - term: id: GO:0000166 label: nucleotide binding evidence_type: IEA original_reference_id: GO_REF:0000104 qualifier: enables supporting_entities: - UniRule:UR001503341 review: action: MODIFY summary: Nucleotide binding is correct but general; the kinase binds ATP as phosphate donor. reason: The conserved glycine-rich loop and Lys101 ATP-binding residue are retained in this model; ATP binding (GO:0005524, also annotated to this entry) is the specific supported term. supported_by: - &id005 reference_id: file:HORSE/MAP2K2/MAP2K2-uniprot.txt record_section: ["FT:BINDING"] supporting_text: 'FT BINDING 101 FT /ligand="ATP"' - *id001 proposed_replacement_terms: - id: GO:0005524 label: ATP binding - term: id: GO:0004672 label: protein kinase activity evidence_type: IEA original_reference_id: GO_REF:0000002 qualifier: enables supporting_entities: - InterPro:IPR008271 review: action: MODIFY summary: Protein kinase activity is correct but general; the specific activity is MAP kinase kinase activity. reason: MAP kinase kinase activity (GO:0004708, is_a descendant of protein kinase activity) is asserted at PAINT node PTN000684494 from which horse MAP2K2 descends, and is directly shown for human MEK2 (PMID:8388392). A0A9L0SHX8 is an alternative horse MAP2K2 gene model that retains human MEK2 residues 1-363 (Lys101, Asp194, Ser222/Ser226 conserved) but replaces human 364-400, including the DVD docking region, with an unrelated tail; the row is judged as a claim about the horse MAP2K2 gene product, and the activity of this particular splice form is untested. supported_by: - &id003 reference_id: file:HORSE/MAP2K2/MAP2K2-bioinformatics/RESULTS-rereview.md supporting_text: 'node PTN000684494 asserts GO:0004708 (F, IBD, negated=false), taxon taxon:2759; 29 seeds; human P36507 among seeds: True' - *id002 - *id001 proposed_replacement_terms: - id: GO:0004708 label: MAP kinase kinase activity - term: id: GO:0004674 label: protein serine/threonine kinase activity evidence_type: IEA original_reference_id: GO_REF:0000120 qualifier: enables supporting_entities: - EC:2.7.11.1 - UniRule:UR000416695 review: action: MODIFY summary: Serine/threonine kinase activity captures only half of the dual-specificity MEK2 reaction. reason: MEK2 phosphorylates both the threonine and the tyrosine of the ERK activation loop (PMID:8388392). GO:0004708 MAP kinase kinase activity (a child of protein serine/threonine/tyrosine kinase activity, not of GO:0004674) is the accurate term; this is a lateral correction rather than a refinement. A0A9L0SHX8 is an alternative horse MAP2K2 gene model that retains human MEK2 residues 1-363 (Lys101, Asp194, Ser222/Ser226 conserved) but replaces human 364-400, including the DVD docking region, with an unrelated tail; the row is judged as a claim about the horse MAP2K2 gene product, and the activity of this particular splice form is untested. supported_by: - *id002 - *id003 - *id004 proposed_replacement_terms: - id: GO:0004708 label: MAP kinase kinase activity - term: id: GO:0004708 label: MAP kinase kinase activity evidence_type: IEA original_reference_id: GO_REF:0000120 qualifier: enables supporting_entities: - ARBA:ARBA00043555 - EC:2.7.12.2 review: action: ACCEPT summary: 'Core function: dual-specificity phosphorylation and activation of ERK1/ERK2.' reason: Horse MAP2K2 is in PANTHER subfamily PTHR47448:SF3 (MAP2K2) and descends from PAINT node PTN000684494, which asserts MAP kinase kinase activity by IBD with human MEK2 among its seeds. Recombinant human MEK2 phosphorylated ERK1 on threonine and tyrosine and activated it >100-fold (PMID:8388392). The catalytic machinery (Lys101, HRD Asp194, activation-loop Ser222/Ser226) and the N-terminal ERK-docking region are conserved in this model. A0A9L0SHX8 is an alternative horse MAP2K2 gene model that retains human MEK2 residues 1-363 (Lys101, Asp194, Ser222/Ser226 conserved) but replaces human 364-400, including the DVD docking region, with an unrelated tail; the row is judged as a claim about the horse MAP2K2 gene product, and the activity of this particular splice form is untested. supported_by: - *id002 - *id003 - *id001 - term: id: GO:0005524 label: ATP binding evidence_type: IEA original_reference_id: GO_REF:0000120 qualifier: enables supporting_entities: - InterPro:IPR000719 - InterPro:IPR017441 - UniRule:UR001503341 review: action: ACCEPT summary: ATP is the phosphate donor of the MEK2 reaction. reason: The protein-kinase ATP-binding signature and Lys101 are retained in this gene model. supported_by: - *id005 - *id001 - *id004 - term: id: GO:0005739 label: mitochondrion evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: located_in supporting_entities: - ARBA:ARBA00026962 review: action: UNDECIDED summary: Localization of MEK2 to the mitochondrion is not established for MAP2K2 specifically. reason: No PAINT node asserts this term for the MAP2K lineage; the electronic row derives from an ARBA rule whose human training annotations cite a review of compartmentalized ERK signaling (PMID:19565474, abstract only in cache) that does not specify MEK2. I cannot verify whether this is a MEK2 property rather than a MEK1- or ERK-specific one, so the row is left UNDECIDED, consistent with the human MAP2K2 review. Experimentally, human MEK2 is cytoplasmic and peripherally membrane-associated via KSR1. supported_by: - &id006 reference_id: file:human/MAP2K2/MAP2K2-uniprot.txt record_section: ["CC:SUBCELLULAR LOCATION"] supporting_text: 'CC -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:10409742}. Membrane CC {ECO:0000269|PubMed:10409742}; Peripheral membrane protein CC {ECO:0000269|PubMed:10409742}. Note=Membrane localization is probably CC regulated by its interaction with KSR1. {ECO:0000269|PubMed:10409742}.' - reference_id: PMID:19565474 supporting_text: "the cascade \nexhibits versatile and dynamic subcellular distribution" - term: id: GO:0005769 label: early endosome evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: located_in supporting_entities: - ARBA:ARBA00028567 review: action: UNDECIDED summary: Localization of MEK2 to the early endosome is not established for MAP2K2 specifically. reason: No PAINT node asserts this term for the MAP2K lineage; the electronic row derives from an ARBA rule whose human training annotations cite a review of compartmentalized ERK signaling (PMID:19565474, abstract only in cache) that does not specify MEK2. I cannot verify whether this is a MEK2 property rather than a MEK1- or ERK-specific one, so the row is left UNDECIDED, consistent with the human MAP2K2 review. Experimentally, human MEK2 is cytoplasmic and peripherally membrane-associated via KSR1. supported_by: - *id006 - reference_id: PMID:19565474 supporting_text: "the cascade \nexhibits versatile and dynamic subcellular distribution" - term: id: GO:0005770 label: late endosome evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: located_in supporting_entities: - ARBA:ARBA00028569 review: action: UNDECIDED summary: Localization of MEK2 to the late endosome is not established for MAP2K2 specifically. reason: No PAINT node asserts this term for the MAP2K lineage; the electronic row derives from an ARBA rule whose human training annotations cite a review of compartmentalized ERK signaling (PMID:19565474, abstract only in cache) that does not specify MEK2. I cannot verify whether this is a MEK2 property rather than a MEK1- or ERK-specific one, so the row is left UNDECIDED, consistent with the human MAP2K2 review. Experimentally, human MEK2 is cytoplasmic and peripherally membrane-associated via KSR1. supported_by: - *id006 - reference_id: PMID:19565474 supporting_text: "the cascade \nexhibits versatile and dynamic subcellular distribution" - term: id: GO:0005925 label: focal adhesion evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: located_in supporting_entities: - ARBA:ARBA00028361 review: action: UNDECIDED summary: Localization of MEK2 to the focal adhesion is not established for MAP2K2 specifically. reason: No PAINT node asserts this term for the MAP2K lineage; the electronic row derives from an ARBA rule whose human training annotations cite a review of compartmentalized ERK signaling (PMID:19565474, abstract only in cache) that does not specify MEK2. I cannot verify whether this is a MEK2 property rather than a MEK1- or ERK-specific one, so the row is left UNDECIDED, consistent with the human MAP2K2 review. Experimentally, human MEK2 is cytoplasmic and peripherally membrane-associated via KSR1. supported_by: - *id006 - reference_id: PMID:19565474 supporting_text: "the cascade \nexhibits versatile and dynamic subcellular distribution" - term: id: GO:0016301 label: kinase activity evidence_type: IEA original_reference_id: GO_REF:0000104 qualifier: enables supporting_entities: - UniRule:UR000416695 review: action: MODIFY summary: Kinase activity is correct but uninformative; the specific activity is MAP kinase kinase activity. reason: GO:0004708 MAP kinase kinase activity is an is_a descendant, supported by PAINT node PTN000684494 and human MEK2 biochemistry (PMID:8388392). supported_by: - *id003 - *id002 proposed_replacement_terms: - id: GO:0004708 label: MAP kinase kinase activity - term: id: GO:0016740 label: transferase activity evidence_type: IEA original_reference_id: GO_REF:0000104 qualifier: enables supporting_entities: - UniRule:UR000416695 review: action: MODIFY summary: Transferase activity is correct but uninformative; the specific activity is MAP kinase kinase activity. reason: GO:0004708 MAP kinase kinase activity is an is_a descendant, supported by PAINT node PTN000684494 and human MEK2 biochemistry (PMID:8388392). supported_by: - *id003 - *id002 proposed_replacement_terms: - id: GO:0004708 label: MAP kinase kinase activity - term: id: GO:0032872 label: regulation of stress-activated MAPK cascade evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: involved_in supporting_entities: - ARBA:ARBA00026638 review: action: UNDECIDED summary: A role in regulation of a stress-activated MAPK cascade (JNK/p38 branches, whose MAP2Ks are MKK3/4/6/7, not MEK2) is not established for MAP2K2 specifically. reason: No PAINT node asserts this term for the MAP2K lineage; the electronic row derives from an ARBA rule whose human training annotations cite a review of compartmentalized ERK signaling (PMID:19565474, abstract only in cache) that does not specify MEK2. I cannot verify whether this is a MEK2 property rather than a MEK1- or ERK-specific one, so the row is left UNDECIDED, consistent with the human MAP2K2 review. supported_by: - reference_id: PMID:19565474 supporting_text: "the cascade \nexhibits versatile and dynamic subcellular distribution" - *id004 - term: id: GO:0090170 label: regulation of Golgi inheritance evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: involved_in supporting_entities: - ARBA:ARBA00028400 review: action: UNDECIDED summary: A role in regulation of Golgi inheritance is not established for MAP2K2 specifically. reason: No PAINT node asserts this term for the MAP2K lineage; the electronic row derives from an ARBA rule whose human training annotations cite a review of compartmentalized ERK signaling (PMID:19565474, abstract only in cache) that does not specify MEK2. I cannot verify whether this is a MEK2 property rather than a MEK1- or ERK-specific one, so the row is left UNDECIDED, consistent with the human MAP2K2 review. supported_by: - reference_id: PMID:19565474 supporting_text: "the cascade \nexhibits versatile and dynamic subcellular distribution" - *id004 - term: id: GO:2000641 label: regulation of early endosome to late endosome transport evidence_type: IEA original_reference_id: GO_REF:0000117 qualifier: involved_in supporting_entities: - ARBA:ARBA00028332 review: action: UNDECIDED summary: A role in regulation of early endosome to late endosome transport is not established for MAP2K2 specifically. reason: No PAINT node asserts this term for the MAP2K lineage; the electronic row derives from an ARBA rule whose human training annotations cite a review of compartmentalized ERK signaling (PMID:19565474, abstract only in cache) that does not specify MEK2. I cannot verify whether this is a MEK2 property rather than a MEK1- or ERK-specific one, so the row is left UNDECIDED, consistent with the human MAP2K2 review. supported_by: - reference_id: PMID:19565474 supporting_text: "the cascade \nexhibits versatile and dynamic subcellular distribution" - *id004 references: - id: GO_REF:0000002 title: Gene Ontology annotation through association of InterPro records with GO terms findings: [] - id: GO_REF:0000104 title: Electronic Gene Ontology annotations created by transferring manual GO annotations between related proteins based on shared sequence features findings: [] - id: GO_REF:0000108 title: Automatic assignment of GO terms using logical inference, based on on inter-ontology links findings: [] - id: GO_REF:0000117 title: Electronic Gene Ontology annotations created by ARBA machine learning models findings: [] - id: GO_REF:0000120 title: Combined Automated Annotation using Multiple IEA Methods findings: [] - id: file:human/MAP2K2/MAP2K2-uniprot.txt title: UniProt record for human MAP2K2 findings: [] reference_review: relevance: HIGH correctness: VERIFIED review_notes: Curated human MEK2 function and localization statements (ECO:0000269 / ECO:0000250). - id: file:HORSE/MAP2K2/MAP2K2-bioinformatics/RESULTS.md title: 'MAP2K2: horse–human sequence comparison' findings: [] reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: Pairwise horse-human comparison from the earlier pass; numbers are correct but the summary omits that the horse product diverges completely after human residue 363. Superseded as primary support by RESULTS-rereview.md; retained for provenance. - id: PMID:8388392 title: Cloning and characterization of two distinct human extracellular signal-regulated kinase activator kinases, MEK1 and MEK2. findings: [] reference_review: relevance: HIGH correctness: VERIFIED review_notes: Direct biochemical demonstration that human MEK2 phosphorylates and activates ERK1. - id: file:HORSE/MAP2K2/MAP2K2-bioinformatics/RESULTS-rereview.md title: 'MAP2K2 (horse): all gene-model products vs human MEK2 P36507 (re-review)' findings: [] reference_review: relevance: HIGH correctness: VERIFIED review_notes: Generated by compare_horse_models_rereview.py from live UniProt/Ensembl and the local PTHR48013 PAINT file. - id: file:HORSE/MAP2K2/MAP2K2-uniprot.txt title: UniProt record for horse A0A9L0SHX8 findings: [] - id: PMID:15866172 title: Conserved docking site is essential for activation of mammalian MAP kinase kinases by specific MAP kinase kinase kinases. findings: [] reference_review: relevance: MEDIUM correctness: VERIFIED review_notes: Abstract only; defines the C-terminal DVD docking site of MAPKKs, which the A0A9L0SHX8 model lacks. - id: PMID:19565474 title: The ERK signaling cascade--views from different subcellular compartments. findings: [] reference_review: relevance: LOW correctness: VERIFIED review_notes: Review article (abstract only) behind the human TAS rows that likely trained the ARBA localization/process rules; does not specify MEK2 in the abstract. core_functions: - description: Dual-specificity MAP kinase kinase that phosphorylates the activation-loop threonine and tyrosine of ERK1/ERK2 in the RAF-MEK-ERK cascade. Inferred for the horse MAP2K2 gene product from PAINT node PTN000684494 and human MEK2 biochemistry; the A0A9L0SHX8 model lacks the C-terminal DVD region and its own activity is untested. molecular_function: id: GO:0004708 label: MAP kinase kinase activity directly_involved_in: - id: GO:0070371 label: ERK1 and ERK2 cascade supported_by: - *id002 - *id003 - *id001 - reference_id: PMID:15866172 supporting_text: DVD site is a stretch of about 20 amino acids immediately on the C-terminal side of the MAPKK catalytic domain suggested_questions: - question: Is the horse MAP2K2 transcript ENSECAT00000136538 (A0A9L0SHX8), whose final exon replaces human MEK2 residues 364-400, supported by RNA-seq junction reads, or is it a gene-build artefact? Which horse transcript encodes the human-like 400-residue MEK2? - question: Should horse MAP2K2 GO annotation be anchored on a corrected full-length gene model (A0A9L0SHX8 residues 1-363 joined to the F6YUU0 C-terminal exon) rather than on the current defective models? - question: Are the ARBA-propagated endosome, Golgi-inheritance and mitochondrial terms MEK2 properties, or MEK1/ERK properties transferred to MEK2 through review-based TAS annotations? suggested_experiments: - hypothesis: Loss of the end of the kinase domain and the DVD docking site in the A0A9L0SHX8 product abolishes RAF-dependent activation of horse MEK2. description: Express full-length horse MEK2 (reconstructed human-like model) and the A0A9L0SHX8 product, co-express with BRAF or RAF1, and compare activation-loop Ser222/Ser226 phosphorylation and phosphorylation of kinase-dead ERK2 in vitro.