MAP3K20

UniProt ID: Q9NYL2
Organism: Homo sapiens
Review Status: COMPLETE
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Gene Description

MAP3K20 (ZAK; also MLK7/MRK) is a stress-activated mitogen-activated protein kinase kinase kinase (MAP3K) of the MLK family. As a serine/threonine protein kinase it phosphorylates the MAP2Ks MKK4/MKK7 (activating JNK) and MKK3/MKK6 (activating p38), driving stress-activated MAPK (JNK and p38) signaling that can promote programmed cell death. The principal isoform ZAKalpha is the proximal sensor of the ribotoxic stress response and directly binds the ribosome by inserting its flexible C-terminus into the intersubunit space (contacting helix 14 of 18S rRNA), acting as a sentinel for colliding ribosomes. Ribosome collisions trigger MAP3K20 autophosphorylation and activation; depending on collision severity it either activates the JNK/p38 cascade to promote cell death or activates EIF2AK4/GCN2 to engage the integrated stress response. ZAKalpha also drives the UV-B-induced NLRP1 inflammasome and pyroptosis by phosphorylating NLRP1. A shorter isoform, ZAKbeta, lacks the ribosome-binding C-terminus and does not sense collisions. MAP3K20 localizes mainly to the cytoplasm/cytosol (with reported nuclear pools and histone H3 Ser-28 kinase activity). It has additional reported roles in DNA-damage checkpoint signaling and cardiac stress responses. Biallelic variants cause split-foot malformation with mesoaxial polydactyly (SFMMP) and centronuclear myopathy 6 (CNM6).

Existing Annotations Review

GO Term Evidence Action Reason
GO:0004674 protein serine/threonine kinase activity
IBA
GO_REF:0000033
ACCEPT
Summary: MAP3K20 is a serine/threonine protein kinase; this is one of its core molecular functions, well supported experimentally and phylogenetically.
Reason: Directly demonstrated kinase activity (multiple EXP/IDA) and consistent with phylogenetic inference; a core function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0005829 cytosol
IBA
GO_REF:0000033
ACCEPT
Summary: MAP3K20 is active in the cytosol, where it senses ribosome collisions and phosphorylates MAP2Ks; well supported.
Reason: Cytosolic activity is consistent with experimental localization and the ribosome-associated sensing function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Cytoplasm, cytosol
GO:0007059 chromosome segregation
IBA
GO_REF:0000033
MARK AS OVER ANNOTATED
Summary: Phylogenetic annotation of chromosome segregation transferred from a PANTHER node that includes NEK6 (Q9HC98). There is no direct experimental evidence that MAP3K20 functions in chromosome segregation.
Reason: This IBA derives from a tree node shared with NEK6 and is not supported by MAP3K20-specific evidence; MAP3K20's documented roles are stress-activated MAPK signaling and ribotoxic stress sensing.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-goa.tsv
PANTHER:PTN002878623|UniProtKB:Q9HC98
GO:0030071 regulation of mitotic metaphase/anaphase transition
IBA
GO_REF:0000033
MARK AS OVER ANNOTATED
Summary: Phylogenetic annotation transferred from a node including NEK6; no MAP3K20-specific evidence for a role in the metaphase/anaphase transition.
Reason: Like the chromosome-segregation IBA, this is transferred from a NEK6-containing node and is not supported by MAP3K20-specific data.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-goa.tsv
PANTHER:PTN002878623|UniProtKB:Q9HC98
GO:0004672 protein kinase activity
IEA
GO_REF:0000002
ACCEPT
Summary: InterPro-based protein kinase activity, a broad parent of the specific serine/threonine and MAP3K activities of MAP3K20.
Reason: Correct but general; the specific MF terms (protein serine/threonine kinase, MAP kinase kinase kinase) are more informative and also annotated.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0004709 MAP kinase kinase kinase activity
IEA
GO_REF:0000120
ACCEPT
Summary: MAP3K20 is a MAP kinase kinase kinase that phosphorylates MKK3/4/6/7; a core molecular function, well supported experimentally.
Reason: Directly demonstrated MAP3K activity (multiple IDA); core function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0005524 ATP binding
IEA
GO_REF:0000120
ACCEPT
Summary: ATP binding by the kinase domain, required for catalysis; directly demonstrated experimentally.
Reason: Standard, experimentally supported catalytic cofactor binding for a protein kinase.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
ATP binding
GO:0005634 nucleus
IEA
GO_REF:0000120
KEEP AS NON CORE
Summary: Electronic nuclear localization; MAP3K20 has reported nuclear pools and histone H3 Ser-28 kinase activity, but its predominant compartment is the cytoplasm.
Reason: Nuclear localization is reported (and consistent with histone-kinase activity) but is secondary to MAP3K20's predominant cytoplasmic localization and ribosome-associated function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
histone kinase by phosphorylating histone H3
GO:0005737 cytoplasm
IEA
GO_REF:0000120
ACCEPT
Summary: Electronic cytoplasmic localization, consistent with the predominant compartment.
Reason: Agrees with EXP/IDA cytoplasm/cytosol localization.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
GO:0106310 protein serine kinase activity
IEA
GO_REF:0000116
ACCEPT
Summary: RHEA/EC-based protein serine kinase activity, consistent with MAP3K20's serine/threonine kinase function.
Reason: Correct and supported by multiple EXP annotations; a core catalytic function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0005515 protein binding
IPI
PMID:15778465
Targeted proteomic analysis of 14-3-3 sigma, a p53 effector ...
KEEP AS NON CORE
Summary: IntAct interaction with 14-3-3 sigma/SFN (P31947). The bare protein binding term is uninformative.
Reason: Records a real interaction but bare protein binding is uninformative and not a core molecular function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Q9NYL2; P31947: SFN
GO:0005515 protein binding
IPI
PMID:16189514
Towards a proteome-scale map of the human protein-protein in...
KEEP AS NON CORE
Summary: IntAct interaction with ZNF567 (Q8N184). The bare protein binding term is uninformative.
Reason: Records a real interaction but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Q8N184: ZNF567
GO:0005515 protein binding
IPI
PMID:21516116
Next-generation sequencing to generate interactome datasets.
KEEP AS NON CORE
Summary: IntAct interaction with ZNF567 (Q8N184). The bare protein binding term is uninformative.
Reason: Records a real interaction but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Q8N184: ZNF567
GO:0005515 protein binding
IPI
PMID:21988832
Toward an understanding of the protein interaction network o...
KEEP AS NON CORE
Summary: IntAct interactions with RPS6KA5 (O75582) and a 14-3-3 protein (P63104/YWHAZ). The bare protein binding term is uninformative.
Reason: Records real interactions but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Q9NYL2; O75582: RPS6KA5
GO:0005515 protein binding
IPI
PMID:28514442
Architecture of the human interactome defines protein commun...
KEEP AS NON CORE
Summary: IntAct interaction with the 14-3-3 protein YWHAZ (P63104). The bare protein binding term is uninformative.
Reason: Records a real interaction but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
P63104: YWHAZ
GO:0005515 protein binding
IPI
PMID:31515488
Extensive disruption of protein interactions by genetic vari...
KEEP AS NON CORE
Summary: IntAct interaction with ZNF567 (Q8N184). The bare protein binding term is uninformative.
Reason: Records a real interaction but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Q8N184: ZNF567
GO:0005515 protein binding
IPI
PMID:33961781
Dual proteome-scale networks reveal cell-specific remodeling...
KEEP AS NON CORE
Summary: BioPlex interaction with the 14-3-3 protein YWHAZ (P63104). The bare protein binding term is uninformative.
Reason: Records a real interaction but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
P63104: YWHAZ
GO:0005515 protein binding
IPI
PMID:35271311
OpenCell: Endogenous tagging for the cartography of human ce...
KEEP AS NON CORE
Summary: IntAct interaction with the 14-3-3 protein YWHAZ (P63104). The bare protein binding term is uninformative.
Reason: Records a real interaction but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
P63104: YWHAZ
GO:0005515 protein binding
IPI
PMID:36931259
A central chaperone-like role for 14-3-3 proteins in human c...
KEEP AS NON CORE
Summary: IntAct interactions with 14-3-3 proteins SFN (P31947) and YWHAZ (P63104). The bare protein binding term is uninformative.
Reason: Records real interactions but bare protein binding is uninformative and not core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Q9NYL2; P31947: SFN
GO:0000287 magnesium ion binding
IEA
GO_REF:0000120
ACCEPT
Summary: Magnesium binding by the kinase domain, required for phosphotransfer; directly demonstrated experimentally.
Reason: Standard catalytic cofactor binding for a protein kinase, with IDA support.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0004674 protein serine/threonine kinase activity
IEA
GO_REF:0000107
ACCEPT
Summary: Ortholog-transferred serine/threonine kinase activity, corroborated by direct evidence; a core molecular function.
Reason: Agrees with multiple EXP/IDA annotations of kinase activity.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0007254 JNK cascade
IEA
GO_REF:0000120
ACCEPT
Summary: MAP3K20 activates the JNK cascade by phosphorylating MKK4/MKK7; well supported experimentally.
Reason: Directly demonstrated JNK-cascade activation (multiple IDA); a core biological process.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0035556 intracellular signal transduction
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Broad intracellular signal transduction; MAP3K20 is a signaling kinase, but more specific MAPK-cascade terms are preferable.
Reason: Correct but general; the specific JNK/p38/stress-activated MAPK cascade terms capture the role more precisely.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0038066 p38MAPK cascade
IEA
GO_REF:0000120
ACCEPT
Summary: MAP3K20 activates the p38 cascade by phosphorylating MKK3/MKK6; well supported experimentally.
Reason: Directly demonstrated p38-cascade activation (multiple IDA); a core biological process.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
leading to activation of the JNK and MAP kinase p38
GO:0042733 embryonic digit morphogenesis
IEA
GO_REF:0000120
KEEP AS NON CORE
Summary: Electronic annotation of embryonic digit morphogenesis, corroborated by the human disease phenotype (split-foot malformation) and IMP evidence.
Reason: Supported by the SFMMP disease phenotype and IMP evidence, but a developmental outcome downstream of MAP3K20's core kinase/stress-signaling function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Split-foot malformation with mesoaxial polydactyly
GO:0051403 stress-activated MAPK cascade
IEA
GO_REF:0000120
ACCEPT
Summary: MAP3K20 is a stress-activated component driving the JNK/p38 (stress-activated MAPK) cascade; a core biological process.
Reason: Strongly supported by experimental evidence (ribotoxic stress, osmotic shock, ionizing radiation); core process.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Stress-activated component of a protein kinase signal
GO:0060173 limb development
IEA
GO_REF:0000107
KEEP AS NON CORE
Summary: Ortholog/IMP-supported role in limb development, consistent with the split-foot malformation phenotype. A developmental outcome.
Reason: Supported by disease genetics but downstream of MAP3K20's core kinase function; non-core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Split-foot malformation with mesoaxial polydactyly
GO:0005829 cytosol
IDA
GO_REF:0000052
ACCEPT
Summary: Direct immunofluorescence (HPA) cytosolic localization, consistent with the predominant compartment and ribosome-associated function.
Reason: IDA-supported cytosolic localization agrees with the documented site of action.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Cytoplasm, cytosol
GO:0005634 nucleus
EXP
PMID:15684425
Phosphorylation of Ser28 in histone H3 mediated by mixed lin...
KEEP AS NON CORE
Summary: Experimental nuclear localization, associated with MAP3K20 histone H3 Ser-28 kinase activity. A secondary localization.
Reason: Experimentally documented nuclear pool (histone-kinase context) but secondary to the predominant cytoplasmic localization.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
histone kinase by phosphorylating histone H3
GO:0005737 cytoplasm
EXP
PMID:15684425
Phosphorylation of Ser28 in histone H3 mediated by mixed lin...
ACCEPT
Summary: Experimental cytoplasmic localization, the predominant compartment.
Reason: Direct experimental support for cytoplasmic localization.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
GO:0106310 protein serine kinase activity
EXP
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Experimentally demonstrated serine kinase activity (original MRK/ZAK characterization).
Reason: Direct experimental support for the core catalytic function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0106310 protein serine kinase activity
EXP
PMID:14521931
Effect of C-terminal truncations on MLK7 catalytic activity ...
ACCEPT
Summary: Experimentally demonstrated serine kinase activity.
Reason: Direct experimental support for the core catalytic function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0106310 protein serine kinase activity
EXP
PMID:26999302
Structure of the Human Protein Kinase ZAK in Complex with Ve...
ACCEPT
Summary: Experimentally demonstrated serine kinase activity.
Reason: Direct experimental support for the core catalytic function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0106310 protein serine kinase activity
EXP
PMID:32289254
ZAKΞ± Recognizes Stalled Ribosomes through Partially Redundan...
ACCEPT
Summary: Experimentally demonstrated serine kinase activity (ZAKalpha ribotoxic stress study).
Reason: Direct experimental support for the core catalytic function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0106310 protein serine kinase activity
EXP
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: Experimentally demonstrated serine kinase activity (ribosome-collision cell-fate study).
Reason: Direct experimental support for the core catalytic function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0106310 protein serine kinase activity
EXP
PMID:35857590
ZAKΞ±-driven ribotoxic stress response activates the human NL...
ACCEPT
Summary: Experimentally demonstrated serine kinase activity (NLRP1 inflammasome study).
Reason: Direct experimental support for the core catalytic function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0000165 MAPK cascade
IDA
PMID:18331592
ZAK: a MAP3Kinase that transduces Shiga toxin- and ricin-ind...
ACCEPT
Summary: MAP3K20 functions in the MAPK cascade; supported by direct evidence.
Reason: Directly demonstrated involvement in MAPK signaling; consistent with the core role, though the specific JNK/p38 cascade terms are more precise.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0006954 inflammatory response
IMP
PMID:18331592
ZAK: a MAP3Kinase that transduces Shiga toxin- and ricin-ind...
KEEP AS NON CORE
Summary: MAP3K20 contributes to inflammatory signaling (consistent with its later-established role in the NLRP1 inflammasome/pyroptosis).
Reason: A genuine downstream outcome of MAP3K20 stress signaling, but broad; the specific pyroptotic/NLRP1 role is captured by other terms.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
leading to activation of the NLRP1 inflammasome and subsequent
GO:0051403 stress-activated MAPK cascade
IDA
PMID:20559024
ZAK is required for doxorubicin, a novel ribotoxic stressor,...
ACCEPT
Summary: Direct evidence for MAP3K20 in the stress-activated MAPK cascade; a core process.
Reason: Directly demonstrated stress-activated MAPK signaling.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Stress-activated component of a protein kinase signal
GO:0004706 JUN kinase kinase kinase activity
IDA
PMID:14521931
Effect of C-terminal truncations on MLK7 catalytic activity ...
ACCEPT
Summary: MAP3K20 acts as a JNK kinase kinase (phosphorylating MKK4/MKK7 upstream of JNK); a specific, core molecular function.
Reason: Directly demonstrated JNKKK activity; a precise, core MF.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0004709 MAP kinase kinase kinase activity
IDA
PMID:15737997
Complete inhibition of anisomycin and UV radiation but not c...
ACCEPT
Summary: Direct evidence for MAP kinase kinase kinase activity; a core molecular function.
Reason: Directly demonstrated MAP3K activity.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0007254 JNK cascade
IDA
PMID:14521931
Effect of C-terminal truncations on MLK7 catalytic activity ...
ACCEPT
Summary: Direct evidence for MAP3K20 activation of the JNK cascade; a core process.
Reason: Directly demonstrated JNK-cascade involvement.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0007254 JNK cascade
IDA
PMID:15737997
Complete inhibition of anisomycin and UV radiation but not c...
ACCEPT
Summary: Direct evidence for MAP3K20 activation of the JNK cascade.
Reason: Directly demonstrated JNK-cascade involvement.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0038066 p38MAPK cascade
IDA
PMID:15737997
Complete inhibition of anisomycin and UV radiation but not c...
ACCEPT
Summary: Direct evidence for MAP3K20 activation of the p38 cascade.
Reason: Directly demonstrated p38-cascade involvement.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
leading to activation of the JNK and MAP kinase p38
GO:0004674 protein serine/threonine kinase activity
IDA
PMID:35857590
ZAKΞ±-driven ribotoxic stress response activates the human NL...
ACCEPT
Summary: Direct evidence for serine/threonine kinase activity (NLRP1 study); core molecular function.
Reason: Directly demonstrated kinase activity.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0004706 JUN kinase kinase kinase activity
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: Direct evidence for JNKKK activity in the ribosome-collision cell-fate study.
Reason: Directly demonstrated JNKKK activity; core MF.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0004709 MAP kinase kinase kinase activity
IDA
PMID:32289254
ZAKΞ± Recognizes Stalled Ribosomes through Partially Redundan...
ACCEPT
Summary: Direct evidence for MAP3K activity in the ZAKalpha ribotoxic stress study.
Reason: Directly demonstrated MAP3K activity; core MF.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0004709 MAP kinase kinase kinase activity
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: Direct evidence for MAP3K activity in the ribosome-collision cell-fate study.
Reason: Directly demonstrated MAP3K activity; core MF.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0004709 MAP kinase kinase kinase activity
IDA
PMID:35857590
ZAKΞ±-driven ribotoxic stress response activates the human NL...
ACCEPT
Summary: Direct evidence for MAP3K activity in the NLRP1 inflammasome study.
Reason: Directly demonstrated MAP3K activity; core MF.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0007254 JNK cascade
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: Direct evidence for JNK-cascade activation upon ribosome collisions.
Reason: Directly demonstrated JNK-cascade involvement in ribotoxic stress.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0030295 protein kinase activator activity
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: MAP3K20 activates EIF2AK4/GCN2 independently of its own kinase activity, acting as a protein kinase activator in the integrated stress response branch.
Reason: Directly demonstrated; MAP3K20 activates GCN2 kinase-independently, a genuine and distinctive molecular function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
MAP3K20 activates EIF2AK4/GCN2
GO:0031098 stress-activated protein kinase signaling cascade
IDA
PMID:35857590
ZAKΞ±-driven ribotoxic stress response activates the human NL...
ACCEPT
Summary: Direct evidence for MAP3K20 in stress-activated protein kinase signaling (NLRP1/ribotoxic stress); a core process.
Reason: Directly demonstrated stress-activated signaling.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Stress-activated component of a protein kinase signal
GO:0038066 p38MAPK cascade
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: Direct evidence for p38-cascade activation upon ribosome collisions.
Reason: Directly demonstrated p38-cascade involvement in ribotoxic stress.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
leading to activation of the JNK and MAP kinase p38
GO:0038066 p38MAPK cascade
IDA
PMID:35857590
ZAKΞ±-driven ribotoxic stress response activates the human NL...
ACCEPT
Summary: Direct evidence for p38-cascade activation in the NLRP1/ribotoxic stress study.
Reason: Directly demonstrated p38-cascade involvement.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
leading to activation of the JNK and MAP kinase p38
GO:0043022 ribosome binding
IDA
PMID:32289254
ZAKΞ± Recognizes Stalled Ribosomes through Partially Redundan...
ACCEPT
Summary: ZAKalpha directly binds the ribosome by inserting its flexible C-terminus into the intersubunit space, acting as the collision sensor; a core, distinctive molecular function.
Reason: Directly demonstrated ribosome binding underlying the ribotoxic-stress sensor role; core MF for ZAKalpha.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
directly binds to the ribosome by inserting its
GO:0043022 ribosome binding
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: ZAKalpha binds the ribosome and preferentially associates with colliding ribosomes; core sensor function.
Reason: Directly demonstrated ribosome binding; core MF for the sensor role.
Supporting Evidence:
PMID:32610081
ZAKΞ± preferentially associates with colliding ribosomes relative to monosomes.
GO:0043068 positive regulation of programmed cell death
IDA
PMID:32289254
ZAKΞ± Recognizes Stalled Ribosomes through Partially Redundan...
ACCEPT
Summary: MAP3K20 acts upstream of programmed cell death triggered by dangerous levels of ribosome collisions (via JNK/p38).
Reason: Directly demonstrated; MAP3K20 promotes programmed cell death in response to ribotoxic stress.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
pathways that promote programmed cell death
GO:0043068 positive regulation of programmed cell death
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: MAP3K20 acts upstream of programmed cell death in the ribosome-collision cell-fate decision.
Reason: Directly demonstrated cell-death-promoting role downstream of ribosome collisions.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
pathways that promote programmed cell death
GO:0046777 protein autophosphorylation
IDA
PMID:32289254
ZAKΞ± Recognizes Stalled Ribosomes through Partially Redundan...
ACCEPT
Summary: Ribosome collisions trigger MAP3K20 autophosphorylation and activation; directly demonstrated.
Reason: Directly demonstrated autophosphorylation, the activation step of the sensor.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
trigger the autophosphorylation and activation of
GO:0051403 stress-activated MAPK cascade
IDA
PMID:32289254
ZAKΞ± Recognizes Stalled Ribosomes through Partially Redundan...
ACCEPT
Summary: Direct evidence for MAP3K20 in the stress-activated MAPK cascade (ribotoxic stress); a core process.
Reason: Directly demonstrated stress-activated MAPK signaling in the ribotoxic stress response.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Stress-activated component of a protein kinase signal
GO:0051403 stress-activated MAPK cascade
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: Direct evidence for MAP3K20 in the stress-activated MAPK cascade (ribosome-collision study).
Reason: Directly demonstrated stress-activated MAPK signaling.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Stress-activated component of a protein kinase signal
GO:0070181 small ribosomal subunit rRNA binding
IDA
PMID:32289254
ZAKΞ± Recognizes Stalled Ribosomes through Partially Redundan...
ACCEPT
Summary: ZAKalpha binds helix 14 of 18S rRNA in the small ribosomal subunit, the molecular basis of its ribosome-collision sensing.
Reason: Directly demonstrated 18S rRNA binding (helix 14); a precise, mechanistically important molecular function for the sensor.
Supporting Evidence:
PMID:32289254
ZAKΞ± binds helix 14 of 18S ribosomal RNA (rRNA).
GO:0070269 pyroptotic inflammatory response
IDA
PMID:35857590
ZAKΞ±-driven ribotoxic stress response activates the human NL...
ACCEPT
Summary: ZAKalpha drives UV-B-induced pyroptosis by activating the NLRP1 inflammasome (directly phosphorylating NLRP1).
Reason: Directly demonstrated; MAP3K20 acts upstream of NLRP1-driven pyroptosis.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
leading to activation of the NLRP1 inflammasome and subsequent
GO:0071493 cellular response to UV-B
IDA
PMID:35857590
ZAKΞ±-driven ribotoxic stress response activates the human NL...
ACCEPT
Summary: ZAKalpha mediates the cellular response to UV-B (ribosome collisions activate MAP3K20, which phosphorylates NLRP1).
Reason: Directly demonstrated UV-B-triggered MAP3K20 signaling; a genuine process.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
triggering the NLRP1 inflammasome in response to UV-B
GO:0140469 GCN2-mediated signaling
IDA
PMID:32610081
Ribosome Collisions Trigger General Stress Responses to Regu...
ACCEPT
Summary: MAP3K20 acts upstream of GCN2-mediated signaling, activating EIF2AK4/GCN2 (kinase-independently) to engage the integrated stress response.
Reason: Directly demonstrated; a distinctive role of MAP3K20 in routing ribosome-collision signals to the ISR via GCN2.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
MAP3K20 activates EIF2AK4/GCN2
GO:0004706 JUN kinase kinase kinase activity
IDA
PMID:12220515
Mixed lineage kinase ZAK utilizing MKK7 and not MKK4 to acti...
ACCEPT
Summary: Direct evidence for JNKKK activity; a precise, core molecular function.
Reason: Directly demonstrated JNKKK activity.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0007254 JNK cascade
IDA
PMID:12220515
Mixed lineage kinase ZAK utilizing MKK7 and not MKK4 to acti...
ACCEPT
Summary: Direct evidence for MAP3K20 in the JNK cascade.
Reason: Directly demonstrated JNK-cascade involvement.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0046777 protein autophosphorylation
IDA
PMID:12220515
Mixed lineage kinase ZAK utilizing MKK7 and not MKK4 to acti...
ACCEPT
Summary: Direct evidence for MAP3K20 autophosphorylation, its activation mechanism.
Reason: Directly demonstrated autophosphorylation.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
trigger the autophosphorylation and activation of
GO:0004706 JUN kinase kinase kinase activity
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Direct evidence for JNKKK activity (original MRK/ZAK characterization).
Reason: Directly demonstrated JNKKK activity.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0007254 JNK cascade
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Direct evidence for MAP3K20 in the JNK cascade.
Reason: Directly demonstrated JNK-cascade involvement.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Activates JNK through
GO:0038066 p38MAPK cascade
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Direct evidence for MAP3K20 in the p38 cascade.
Reason: Directly demonstrated p38-cascade involvement.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
leading to activation of the JNK and MAP kinase p38
GO:1904291 positive regulation of mitotic DNA damage checkpoint
IDA
PMID:15342622
The stress kinase MRK contributes to regulation of DNA damag...
KEEP AS NON CORE
Summary: MAP3K20 may regulate the S/G2 DNA-damage checkpoint via phosphorylation of CHEK2; a context-specific role.
Reason: Experimentally reported checkpoint role (CHEK2 phosphorylation) but distinct from MAP3K20's predominant stress-activated MAPK/ribotoxic-stress function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
regulation of S and G2 cell cycle
GO:0051403 stress-activated MAPK cascade
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Direct evidence for MAP3K20 in the stress-activated MAPK cascade.
Reason: Directly demonstrated stress-activated MAPK signaling; core process.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Stress-activated component of a protein kinase signal
GO:0071480 cellular response to gamma radiation
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
KEEP AS NON CORE
Summary: MAP3K20 (MRK) mediates a response to gamma/ionizing radiation, consistent with its stress-activated role.
Reason: A genuine stress-response context but one of several stress stimuli; the ribotoxic stress / stress-activated MAPK cascade is the core.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
osmotic shock and ionizing
GO:0042733 embryonic digit morphogenesis
IMP
PMID:26755636
Exome sequencing and CRISPR/Cas genome editing identify muta...
KEEP AS NON CORE
Summary: Loss-of-function variants cause split-foot malformation, implicating MAP3K20 in embryonic digit morphogenesis.
Reason: Supported by human disease genetics (SFMMP) but a developmental outcome downstream of the core kinase function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Split-foot malformation with mesoaxial polydactyly
GO:0060173 limb development
IMP
PMID:26755636
Exome sequencing and CRISPR/Cas genome editing identify muta...
KEEP AS NON CORE
Summary: Loss-of-function variants cause limb/foot malformation, implicating MAP3K20 in limb development.
Reason: Supported by disease genetics but downstream of the core kinase function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Split-foot malformation with mesoaxial polydactyly
GO:0003723 RNA binding
HDA
PMID:22681889
The mRNA-bound proteome and its global occupancy profile on ...
MARK AS OVER ANNOTATED
Summary: High-throughput RNA-interactome capture annotated MAP3K20 as RNA-binding. This is consistent with (and likely reflects) its specific 18S rRNA / ribosome binding; the bare RNA binding term is uninformative.
Reason: Generic RNA binding from a proteome-wide screen; the biologically meaningful activity is the specific small ribosomal subunit rRNA binding (GO:0070181) already annotated.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
directly binds to the ribosome by inserting its
GO:0000077 DNA damage checkpoint signaling
IMP
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
KEEP AS NON CORE
Summary: MAP3K20 (MRK) was implicated in DNA-damage checkpoint signaling after gamma irradiation; a context-specific role.
Reason: Reported checkpoint role, but distinct from and secondary to MAP3K20's predominant ribotoxic-stress / stress-activated MAPK function.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
regulation of S and G2 cell cycle
GO:0004709 MAP kinase kinase kinase activity
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Direct evidence for MAP3K activity (original MRK/ZAK characterization); core molecular function.
Reason: Directly demonstrated MAP3K activity.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0008219 cell death
NAS
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
KEEP AS NON CORE
Summary: Broad cell-death annotation; MAP3K20 promotes programmed cell death in response to stress. The more specific positive regulation of programmed cell death is preferable.
Reason: Correct in spirit but a broad term; the specific programmed-cell-death terms capture the role.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
promotes programmed cell death
GO:0030154 cell differentiation
NAS
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
MARK AS OVER ANNOTATED
Summary: Broad cell-differentiation annotation (non-author statement) with no specific MAP3K20 mechanism documented.
Reason: Very general NAS annotation not supported by specific MAP3K20 evidence; its documented roles are stress-activated signaling and ribotoxic stress sensing.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Stress-activated component of a protein kinase signal
GO:0000287 magnesium ion binding
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Direct evidence for magnesium binding by the kinase domain.
Reason: Standard catalytic cofactor binding, experimentally supported.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0005524 ATP binding
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: Direct evidence for ATP binding by the kinase domain.
Reason: Standard catalytic cofactor binding, experimentally supported.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
ATP binding
GO:0005737 cytoplasm
ISS
GO_REF:0000024
ACCEPT
Summary: Sequence-similarity-based cytoplasmic localization, consistent with the predominant compartment.
Reason: Agrees with experimental cytoplasm/cytosol localization.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
SUBCELLULAR LOCATION: Cytoplasm
GO:0006468 protein phosphorylation
IDA
PMID:11836244
MRK, a mixed lineage kinase-related molecule that plays a ro...
ACCEPT
Summary: MAP3K20 phosphorylates substrate proteins; protein phosphorylation is the direct process outcome of its kinase activity.
Reason: Directly supported process annotation for a protein kinase.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
Acts by catalyzing phosphorylation of MAP kinase
GO:0043065 positive regulation of apoptotic process
IDA
PMID:10924358
Cloning and expression of ZAK, a mixed lineage kinase-like p...
ACCEPT
Summary: MAP3K20 positively regulates apoptosis in response to stress, consistent with its programmed-cell-death-promoting role.
Reason: Directly demonstrated pro-apoptotic role downstream of MAP3K20 stress signaling.
Supporting Evidence:
file:human/MAP3K20/MAP3K20-uniprot.txt
promotes programmed cell death

Core Functions

Stress-activated serine/threonine MAP kinase kinase kinase that phosphorylates MAP2Ks (MKK4/MKK7 and MKK3/MKK6) to activate the JNK and p38 (stress-activated) MAPK cascades, driving stress responses that can promote programmed cell death.

Cellular Locations:
Supporting Evidence:
  • file:human/MAP3K20/MAP3K20-uniprot.txt
    Acts by catalyzing phosphorylation of MAP kinase
  • file:human/MAP3K20/MAP3K20-uniprot.txt
    leading to activation of the JNK and MAP kinase p38

Proximal sensor of ribosome collisions in the ribotoxic stress response; isoform ZAKalpha directly binds the ribosome (inserting its C-terminus into the intersubunit space and contacting helix 14 of 18S rRNA), autophosphorylates upon collisions, and routes the signal to the JNK/p38 cell-death cascade or to GCN2-mediated integrated stress response.

Molecular Function:
ribosome binding
Cellular Locations:
Supporting Evidence:
  • file:human/MAP3K20/MAP3K20-uniprot.txt
    directly binds to the ribosome by inserting its
  • PMID:32289254
    ZAKΞ± binds helix 14 of 18S ribosomal RNA (rRNA).

Stress-activated MAPK signaling that triggers programmed cell death and, in response to UV-B/ribotoxic stress, the NLRP1 inflammasome and pyroptosis through direct NLRP1 phosphorylation.

Cellular Locations:
Supporting Evidence:
  • file:human/MAP3K20/MAP3K20-uniprot.txt
    triggering the NLRP1 inflammasome in response to UV-B
  • file:human/MAP3K20/MAP3K20-uniprot.txt
    pathways that promote programmed cell death

References

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Suggested Questions for Experts

Q: What determines whether ribosome collisions sensed by ZAKalpha route to the pro-death JNK/p38 cascade versus the pro-survival GCN2/integrated stress response (e.g. collision density, duration, or ribosome ubiquitination state)?

Q: How do the centronuclear myopathy (CNM6) and split-foot malformation (SFMMP) phenotypes relate mechanistically to defects in ribotoxic stress sensing versus other MAP3K20 functions?

Q: Does the kinase-independent activation of GCN2 by MAP3K20 reflect a scaffolding interaction, and what is its structural basis?

Suggested Experiments

Experiment: Compare ZAKalpha (ribosome-binding) and ZAKbeta (C-terminus-deleted) knock-in cells for ribotoxic-stress-induced p38/JNK activation, GCN2/ISR engagement, and cell-fate outcomes to dissect collision-sensing-dependent versus -independent signaling.

Experiment: Structure-guided mutations in the ZAKalpha C-terminal ribosome-sensing domains (intersubunit insertion; 18S rRNA helix-14 contact) tested for collision binding and downstream MAPK/NLRP1 activation.

Experiment: Patient-derived myotubes carrying CNM6 variants assayed for ribotoxic stress signaling and proteostasis to test whether impaired ZAKalpha surveillance contributes to the myopathy.

πŸ“š Additional Documentation

Notes

(MAP3K20-notes.md)

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Pn Notes

(MAP3K20-pn-notes.md)

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