| 1998 |
PRAK (MAPKAPK5) is a serine/threonine kinase activated by p38α and p38β both in vitro and in vivo; Thr182 was identified as the regulatory phosphorylation site. Activated PRAK phosphorylates small heat shock protein 27 (HSP27) at physiologically relevant sites. |
In vitro kinase assay, in-gel kinase assay, mutagenesis of Thr182, co-immunoprecipitation |
The EMBO journal |
High |
9628874
|
| 1998 |
MAPKAPK5 can be phosphorylated and activated by ERK and p38 kinase in vitro (but not by JNK); phosphorylation by ERK and p38 increased its activity 9- and 15-fold respectively. Recombinant MAPKAPK5 phosphorylates a peptide derived from the regulatory light chain of myosin II. |
In vitro kinase assay with recombinant proteins |
Biochemical and biophysical research communications |
Medium |
9480836
|
| 2003 |
Unlike MK2, endogenous MK5 does not interact with or chaperone p38 MAPK, is not activated by extracellular stresses such as arsenite or sorbitol, and cannot phosphorylate Hsp27 in vitro and in vivo in fibroblasts derived from knockout mice. |
MK5 knockout mouse fibroblasts, in vitro kinase assay, co-immunoprecipitation |
Molecular and cellular biology |
High |
14560018
|
| 2003 |
PRAK subcellular localization is controlled by p38α and p38β through docking interactions: ectopically expressed PRAK resides in the nucleus but is redistributed to cytoplasm by co-expression of p38α/β. p38-mediated phosphorylation of PRAK promotes its nuclear export, while nuclear import is p38-independent. PRAK contains functional NES and NLS motifs required for nucleocytoplasmic shuttling. |
Immunostaining, nuclear export/import assays, docking groove and docking-site mutants, leptomycin B treatment |
Molecular biology of the cell |
High |
12808055
|
| 2004 |
ERK3 specifically interacts with MK5, causing nuclear exclusion of both proteins and ERK3-dependent phosphorylation and activation of MK5 in vitro and in vivo. Endogenous MK5 activity is reduced by siRNA knockdown of ERK3 and in ERK3-/- fibroblasts. MK5 acts as a chaperone for ERK3 (MK5 depletion dramatically reduces ERK3 protein levels). |
Co-immunoprecipitation, siRNA knockdown, ERK3 knockout fibroblasts, in vitro kinase assay, immunofluorescence |
The EMBO journal |
High |
15577943
|
| 2004 |
ERK3 scaffolds MK5 activation independent of ERK3 enzymatic activity but dependent on MK5 catalytic activity and the C-terminal extension of ERK3. ERK3-MK5 interaction causes nuclear-to-cytoplasmic translocation of MK5. MK5 deletion causes strong reduction of ERK3 protein levels and embryonic lethality at ~E11 in mice. |
Co-immunoprecipitation, kinase-dead mutants, MK5 knockout mouse, immunofluorescence, embryo analysis |
The EMBO journal |
High |
15538386
|
| 2006 |
ERK4 (MAPK4), a stable protein, binds endogenous MK5 and translocates MK5 to the cytoplasm. Unlike ERK3, ERK4 requires its own catalytic activity to activate MK5 (direct phosphorylation). ERK4 can dimerize/oligomerize with ERK3, enabling ERK4 to relay activation to MK5 in the context of kinase-dead ERK3. |
Co-immunoprecipitation, kinase-dead mutants, transfection in HEK293 cells, immunofluorescence |
The Journal of biological chemistry |
Medium |
16973613
|
| 2007 |
PRAK activates p53 by direct phosphorylation, mediating oncogenic ras-induced senescence downstream of p38 MAPK. PRAK deficiency in mice enhances DMBA-induced skin carcinogenesis coinciding with impaired senescence induction. |
In vitro kinase assay, PRAK knockout mice, primary cell transformation assay, DMBA skin carcinogenesis model |
Cell |
High |
17254968
|
| 2007 |
PKA catalytic subunit Cα interacts with MK5 (but not MK2) in vivo, increases MK5 kinase activity and phosphorylation, and induces transient nuclear export of MK5, which requires kinase activity of both Cα and MK5 and Cα nuclear entry. MK5 is required for PKA-induced F-actin rearrangement in PC12 cells. |
Co-immunoprecipitation, kinase assays, siRNA depletion, constitutively active MK5 expression, fluorescence microscopy |
The Journal of biological chemistry |
High |
17947239
|
| 2007 |
14-3-3ε interacts with MK5 in vivo and in vitro, and this interaction inhibits MK5-mediated phosphorylation of HSP27, thereby disrupting F-actin polymerization and inhibiting MK5-induced cell migration. |
Co-immunoprecipitation, in vitro binding assay, transfection, cell migration assay |
Cellular signalling |
Medium |
17728103
|
| 2008 |
Activation loop phosphorylation of ERK3 and ERK4 (at their SEG motif) is required for formation of stable active complexes with MK5 and for efficient cytoplasmic redistribution of ERK3/ERK4-MK5 complexes. This phosphorylation is constitutive in resting cells and can be modulated by MK5 interaction. |
Phospho-specific antibodies, mutagenesis of SEG motif, co-immunoprecipitation, subcellular fractionation |
Journal of cellular physiology |
Medium |
18720373
|
| 2008 |
ERK4 Ser186 (in its SEG motif) is phosphorylated in vivo by an upstream kinase (not autophosphorylation); Ser186 phosphorylation is required for ERK4 to interact with, activate, and cytoplasmatically anchor MK5. MK5 binding facilitates Ser186 phosphorylation and stabilizes the ERK4-MK5 complex. |
Mutagenesis of Ser186, phospho-specific antibodies, co-immunoprecipitation, kinase assays |
The Biochemical journal |
Medium |
18248330
|
| 2008 |
Distinct amino acid residues in p38α (Asp145, Leu156) versus p38β (Gly145, Val156) determine the differential subcellular localization of p38α-PRAK (nuclear) versus p38β-PRAK (cytosolic) complexes. Nuclear localization of PRAK is required for its function in inhibiting NIH3T3 cell proliferation. |
Chimeric and point mutants of p38α/β, immunofluorescence, nuclear import/export assays, cell proliferation assay |
The Journal of biological chemistry |
Medium |
18268017
|
| 2009 |
ERK3 and ERK4 contain a novel MK5-interaction motif (FRIEDE) in their L16 C-terminal extension, distinct from the classical CD domain. A single I→K substitution in FRIEDE abolishes binding, activation, and translocation of MK5 by both ERK3 and ERK4. Activation loop phosphorylation of ERK3/4 gates accessibility of the FRIEDE motif. |
Peptide overlay assays, mutagenesis of FRIEDE motif, co-immunoprecipitation, kinase activation assays |
The Journal of biological chemistry |
High |
19473979
|
| 2009 |
MK5 interacts with HSP27 in vivo and phosphorylates HSP27 at Ser78 and Ser82 in cells. Expression of constitutively active MK5 induces F-actin rearrangement in PC12 cells, and co-expression of non-phosphorylatable Hsp27-3A abrogates this effect. |
Co-immunoprecipitation, phospho-specific antibodies, constitutively active MK5 expression, siRNA depletion of Hsp27, fluorescence microscopy |
Cellular signalling |
Medium |
19166925
|
| 2010 |
PKA phosphorylates MK5 at Ser115 in vitro; PKA-induced nuclear export of MK5 requires Ser115 phosphorylation (S115A blocks PKA-induced export; S115D phosphomimetic causes cytoplasmic localization in resting cells). Mutations in Ser115 affect MK5 biological properties. |
In vitro kinase assay, mutagenesis of Ser115, nuclear export assay, phosphomimetic mutant analysis |
Cellular and molecular life sciences |
Medium |
20734105
|
| 2011 |
MK5 regulates translation of c-Myc by promoting expression of miR-34b and miR-34c through phosphorylation of FoxO3a, which promotes nuclear localization of FoxO3a enabling it to induce miR-34b/c expression. This establishes a MK5-FoxO3a-miR-34b/c negative feedback loop that suppresses Myc and is disrupted in colorectal cancer. |
siRNA kinome screen, reporter assays, FoxO3a phosphorylation assay, nuclear localization of FoxO3a by immunofluorescence, miRNA expression analysis |
Molecular cell |
High |
21329882
|
| 2011 |
MK5 activates FoxO3a by phosphorylation in developing B cells; this MK5-mediated phosphorylation of Foxo1 at Ser215 is required for transcriptional activation of Rag genes. MK5 is necessary and sufficient to activate Rag transcription in pro-B cells. |
Foxo1 mutant panel screen, in vitro and in vivo phosphorylation, B cell transformation and primary pro-B cell assays |
The Journal of experimental medicine |
Medium |
23878308
|
| 2011 |
The p38β-PRAK cascade mediates energy-starvation-induced suppression of mTORC1. PRAK directly phosphorylates Rheb at Ser130, impairing Rheb nucleotide-binding ability and inhibiting Rheb-mediated mTORC1 activation. This pathway operates independently of AMPK-TSC2 and AMPK-Raptor pathways. |
In vitro kinase assay, Rheb phosphorylation mapping, siRNA depletion, mTORC1 activity assays, cell-size measurement |
Nature cell biology |
High |
21336308
|
| 2012 |
In IGF2BP1-expressing tumor cells, inhibition of MAPK4 mRNA translation by IGF2BP1 antagonizes MK5 activation and prevents MK5-mediated HSP27 phosphorylation, which would otherwise sequester actin monomers, reducing availability of G-actin for F-actin polymerization and cell migration. |
Translational inhibition assay, MK5 activity measurements, HSP27 phosphorylation, F-actin/G-actin assays, cell migration assay |
Genes & development |
Medium |
22279049
|
| 2013 |
Tip60 acetylates PRAK at K364 in a manner that depends on prior phosphorylation of both Tip60 (Thr158 by p38) and PRAK by p38, inducing PRAK kinase activity. This defines a cascade: ras→p38→Tip60 acetylation→PRAK activation→oncogene-induced senescence. |
In vitro acetyltransferase assay, mutagenesis of Tip60-Thr158 and PRAK-K364, co-immunoprecipitation, senescence assays |
Molecular cell |
High |
23685072
|
| 2013 |
MK5 physically interacts with Hsp40/DnaJB1 in cells via C-terminal regions of both proteins and phosphorylates Hsp40/DnaJB1 at Ser149 and/or Ser151 and Ser171 in vivo. MK5 modestly stimulates Hsp40/Hsp70 ATPase activity and enhances Hsp40/DnaJB1-mediated repression of HSF1-driven transcription. |
Co-immunoprecipitation, in vitro kinase assay, phospho-specific antibodies, ATPase activity assay, luciferase reporter assay |
The international journal of biochemistry & cell biology |
Medium |
24309468
|
| 2014 |
PRAK interacts with DJ-1 (via yeast two-hybrid confirmed by Co-IP) and phosphorylates DJ-1 in vitro and in vivo upon H2O2 stimulation. In PRAK-/- cells, DJ-1 translocates from nucleus to cytoplasm after H2O2, losing its ability to sequester the pro-apoptotic protein Daxx in the nucleus, leading to cell death. |
Yeast two-hybrid, Co-immunoprecipitation, in vitro kinase assay, immunofluorescence in PRAK+/+ vs PRAK-/- cells, Daxx localization assay |
Oxidative medicine and cellular longevity |
Medium |
25383140
|
| 2014 |
PRAK is phosphorylated by Src kinase, directing PRAK to focal adhesions. Overexpressed PRAK inhibits cell motility by phosphorylating FAK at Y861, thereby impairing FAK activation. PRAK and Src/FAK interact physically in focal adhesions. |
In situ kinase overlay assay, co-immunoprecipitation, phospho-specific antibodies for FAK Y861, motility assay, immunofluorescence |
Journal of cancer biology & research |
Low |
26042227
|
| 2016 |
PRAK interacts with RAGE (receptor for advanced glycation end-products) and Aβ treatment increases PRAK phosphorylation and PRAK-RAGE interaction. PRAK knockdown rescues mTORC1 inactivation induced by Aβ and decreases Aβ-induced autophagosome formation, placing PRAK in the RAGE-mTORC1-autophagy pathway in Alzheimer's disease models. |
Co-immunoprecipitation, siRNA knockdown, mTORC1 activity assay, autophagosome quantification |
Molecular neurodegeneration |
Low |
26758977
|
| 2019 |
MK5 physically interacts with YAP and counteracts CK1δ/ε-mediated YAP ubiquitination and degradation in a LATS1/2-independent manner. MK5 kinase activity is essential for protecting YAP from ubiquitin-mediated degradation and cytoplasmic retention. |
RNAi screen, co-immunoprecipitation, ubiquitination assay, kinase-dead MK5 mutant, xenograft model |
Cancer research |
Medium |
31578200
|
| 2021 |
Loss-of-function variants in MAPKAPK5 cause a developmental disorder with neurological, cardiac, and digital anomalies. Patient-derived fibroblasts lack MAPKAPK5 protein isoforms, have reduced ERK3 levels, and show impaired F-actin recovery after latrunculin B treatment, supporting a role of MAPKAPK5 in F-actin polymerization. |
Exome sequencing, patient-derived fibroblast functional assays (F-actin recovery after latrunculin B treatment), Western blot |
Genetics in medicine |
Medium |
33442026
|
| 2021 |
PRAK deficiency abrogates lung metastases in PyMT mice and after intravenous injection of tumor cells, with no effect on primary tumor growth. Loss of PRAK leads to pronounced inhibition of HIF-1α protein synthesis, possibly due to reduced mTORC1 activities. |
Prak knockout mouse models, PyMT mammary tumor model, intravenous tumor injection, Western blot for HIF-1α and mTORC1 components |
Nature communications |
Medium |
33741957
|
| 2022 |
TLK1 phosphorylates MK5 at three residues (S160, S354, S386), resulting in MK5 activation. MK5-S354A or kinase-dead MK5 in MK5-/- MEF cells fails to restore motility compared to wild-type MK5. The TLK1-MK5 axis promotes prostate cancer cell motility and invasion. |
In vitro kinase assay, phospho-specific antibody for pMK5-S354, mutagenesis, MK5 knockout MEF rescue, motility assay |
Molecular oncology |
Medium |
35064619
|
| 2022 |
ERK3-MK5 signaling promotes FoxO3 degradation by MK5-mediated direct phosphorylation of FoxO3, reducing FoxO3 association with MyoD and inhibiting myogenic differentiation. Loss of ERK3 or MK5 causes precocious myoblast differentiation; depletion of FoxO3 rescues this premature differentiation. |
In vitro kinase assay, genetic inactivation of ERK3 (Mapk6KD/KD mice) and MK5, C2C12 and primary myoblast differentiation assays, FoxO3 depletion rescue experiments |
Journal of cellular physiology |
High |
35141958
|
| 2023 |
PRAK phosphorylates NRF2 at Ser558, enhancing NRF2 protein stability independent of ubiquitination. Loss of PRAK increases cellular ROS, disrupts glycolysis and PKM2-dependent STAT3 phosphorylation, and impairs Th17 cell differentiation. Prak KO mice show resistance to EAE but impaired antitumor immunity. |
In vitro kinase assay identifying NRF2 as MK5/PRAK substrate, Prak knockout mice, Th17 differentiation assays, ROS measurement, glycolysis assays |
PNAS |
Medium |
37126714
|
| 2012 |
Septin 8 is an interaction partner and in vitro substrate of MK5; the interaction is confirmed by GST pulldown, Co-IP, and FRET. MK5 phosphorylates Ser242 and Ser271 on Septin 8 in vitro. MK5 and Septin 8 co-localize in the perinuclear area, cell protrusions, and with synaptophysin-positive vesicles. |
Yeast two-hybrid, GST pulldown, Co-immunoprecipitation, FRET, in vitro kinase assay, confocal microscopy |
World journal of biological chemistry |
Medium |
22649572
|
| 2026 |
FXR1 drives retention of exon 6 in MK5 pre-mRNA, generating a long kinase-competent MK5-L isoform in HCC. MK5-L phosphorylates GSK3β, activating Wnt/β-catenin signaling and promoting HCC progression and metastasis. |
Alternative splicing analysis, in vitro kinase assay, GSK3β phosphorylation, Wnt/β-catenin reporter, FXR1 knockdown/overexpression, xenograft model, antisense oligonucleotide therapeutic intervention |
Cancer science |
Medium |
41954085
|
| 2025 |
Microglial MK5 regulates the neuroinflammatory response to ischemic stroke by controlling phosphorylation of HSP27 and NF-κB. Microglia-specific MK5 knockout exacerbates neurological deficits, increases infarct volume, upregulates pro-inflammatory cytokines, and reduces HSP27 phosphorylation while increasing NF-κB phosphorylation. |
Microglia-specific conditional MK5 knockout, MCAO mouse model, OGD/R BV2 cell model, Western blot for pHSP27 and pNF-κB, cytokine qPCR, immunofluorescence |
CNS neuroscience & therapeutics |
Medium |
40237440
|