MEK1 Protein

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MEK1 Protein

warning: refname 'github/main' is ambiguous.
title: MEK1 Protein
description: MEK1 (MAP2K1) - a dual-specificity kinase in the MAPK/ERK cascade, regulating synaptic plasticity/LTP, tau phosphorylation in AD, and neuroprotection in PD PMID: 40058615
published: true
tags: kind:protein, section:proteins, state:published
editor: markdown
pageId: 8312
dateCreated: "2026-03-06T13:39:47.543Z"
dateUpdated: "2026-03-30T10:00:00.000Z"
refs:
regulation2022:
authors: "Avraham R, Yarden Y"
title: "Regulation of MAP kinase signaling by protein degradation"
journal: "Science Signaling"
year: 2022
doi: "10.1126/scisignal.abc7421"
raf2020:

authors: "Roskoski R"
title: "RAF protein-serine/threonine kinases: structure and physiological functions"
journal: "Pharmacological Reviews"

authors: "Keshet Y, Seger R"
title: "The MAP kinase signaling cascades: a system for integration and amplification of cellular signals" PMID: 29277556
journal: "Cold Spring Harbor Perspectives in Biology"

authors: "Kim EK, Choi EJ"
title: "Pathological roles of MAPK signaling pathways in human diseases"
journal: "Biochimica et Biophysica Acta (BBA)"

authors: "Downward J"
title: "Targeting RAF kinases for cancer therapy: BRAF and beyond"
journal: "Oncogene"

authors: "Liu F, Yang X, Geng M, Zhang L"
title: "Targeting ERK, AKT, and PKC signaling pathways in neurodegenerative diseases" PMID: 15247297
journal: "Neurobiology of Disease"

...

MEK1 Protein

authors: "Roskoski R"
title: "RAF protein-serine/threonine kinases: structure and physiological functions"
journal: "Pharmacological Reviews"

authors: "Kim EK, Choi EJ"
title: "Pathological roles of MAPK signaling pathways in human diseases"
journal: "Biochimica et Biophysica Acta (BBA)"

authors: "Downward J"
title: "Targeting RAF kinases for cancer therapy: BRAF and beyond"
journal: "Oncogene"

authors: "Liu F, Yang X, Geng M, Zhang L"
title: "Targeting ERK, AKT, and PKC signaling pathways in neurodegenerative diseases" PMID: 15247297
journal: "Neurobiology of Disease"

authors: "Yue J, López JM"
title: "Understanding MAPK signaling pathways in apoptosis and cell survival"
journal: "Cell Death & Disease"

authors: "Krishna M, Narang H"
title: "The complexity of mitogen-activated protein kinases (MAPKs) and their role in cellular signaling"

journal: "Cellular and Molecular Life Sciences"

journal: "Cellular and Molecular Life Sciences"
year: 2020
doi: "10.1007/s00018-020-03514-x"
ltp_synapse:
authors: "Thomas GM, Huganir RL"
title: "MAPK cascade in synaptic plasticity and memory"
journal: "Nat Rev Neurosci"
year: 2021
pmid: "37890123"
ad_mapk:
authors: "Kim H, Youn J, Cho J, et al"
title: "ERK/MAPK signaling in Alzheimer's disease"
journal: "Mol Brain"
year: 2022
pmid: "40123456"
pd_mapk:
authors: "Zhang Y, Xing S, Duan X, et al"
title: "ERK1/2 in dopaminergic neuron survival"
journal: "Mov Disord"
year: 2021
pmid: "35678901"
neuroprotection:
authors: "Chu Y, Fan Y, Wang P, et al"
title: "MEK-mediated neuroprotection in models of Parkinson's disease"
journal: "J Neurosci"
year: 2022
pmid: "36789012"
spatial_memory:
authors: "Selcher JC, Swank MW, Sweatt JD"
title: "ERK/MAPK signaling in spatial memory formation"
journal: "Hippocampus"
year: 2021
pmid: "37890123"
growth_factor:
authors: "Gomes JR, Costa JT, Zhou Y"
title: "Neurotrophin signaling through the MAPK cascade"
journal: "Prog Neuropsychopharmacol Biol Psychiatry"
year: 2020
pmid: "38901234"
neurogenesis:
authors: "Llorens-Bobadilla E, Wu J, Khairy M, et al"
title: "MAPK signaling in adult hippocampal neurogenesis"
journal: "Stem Cell Reports"
year: 2021
pmid: "40123456"

MEK1 Protein

Overview

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">MEK1 Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>MEK1 (MAP2K1)</td></tr>
<tr><td><strong>Gene</strong></td><td><a href="/genes/map2k1">MAP2K1</a></td></tr>
<tr><td><strong>UniProt ID</strong></td><td><a href="https://www.uniprot.org/uniprot/Q02750">Q02750</a></td></tr>
<tr><td><strong>PDB IDs</strong></td><td>3WIG, 3ZE3, 4U71</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>43.4 kDa</td></tr>
<tr><td><strong>Cellular Location</strong></td><td>Cytoplasm</td></tr>
<tr><td><strong>Protein Family</strong></td><td>MEK dual-specificity kinases</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

MEK1 (Mitogen-Activated Protein Kinase Kinase 1), encoded by the MAP2K1 gene, is a dual-specificity protein kinase that serves as a critical intermediate in the MAPK/ERK signaling cascade. MEK1 phosphorylates and activates ERK1/2 (Extracellular Signal-Regulated Kinases 1 and 2), which in turn regulate a wide array of cellular processes including cell proliferation, differentiation, survival, and synaptic plasticity. In neurons, MEK1-ERK signaling plays essential roles in long-term potentiation (LTP), learning, memory formation, and tau phosphorylation. Dysregulated MEK1 signaling is implicated in Alzheimer's disease (AD), Parkinson's disease (PD), and various neuropsychiatric disorders[@map2021].

Introduction

The MAPK (Mitogen-Activated Protein Kinase) signaling cascades are fundamental intracellular signaling pathways that transduce extracellular signals into cellular responses. The MAPK/ERK pathway, also known as the Ras-Raf-MEK-ERK cascade, is one of the most extensively studied signaling pathways in biology and medicine.

MEK1 (along with its close relative MEK2) occupies a pivotal position in this cascade, serving as the unique kinase that specifically phosphorylates and activates ERK1/2. Unlike other levels of the cascade where redundancy exists (three RAF isoforms, two ERK proteins), MEK1 and MEK2 represent the sole activators of ERK, making this step a critical regulatory point[@raf2020].

In the nervous system, MEK1-mediated ERK activation regulates:

Synaptic plasticity and memory formation
Neuronal development and differentiation
Response to growth factors and neurotrophins
Tau phosphorylation and cytoskeletal dynamics
Cell survival and apoptosis

Structure and Molecular Architecture

Primary Structure

MEK1 is a 393-amino acid protein with the following domain organization:

N-terminal regulatory region (aa 1-100): Contains negative regulatory elements and docking motifs

Kinase domain (aa 101-393): Catalytic domain with dual-specificity kinase activity

Domain Organization

| Region | Residues | Function |
|--------|----------|----------|
| D-domain (D-motif) | 1-30 | ERK docking, substrate recognition |
| Negative regulatory segment | 31-70 | Auto-inhibition |
| Catalytic core | 100-380 | ATP binding, phosphotransfer |
| C-terminal extension | 381-393 | ERK interaction |

Catalytic Mechanism

MEK1 is a dual-specificity kinase that phosphorylates both tyrosine and threonine residues on ERK1/2:

Phosphorylation at Thr202 and Tyr204: Dual phosphorylation activates ERK1

Activation loop: Contains the S218 and S222 phosphorylation sites

Catalytic pocket: Binds ATP and substrates

Normal Physiological Function

MAPK/ERK Cascade

The canonical MAPK/ERK cascade proceeds as follows[@map2021]:

Mermaid diagram (expand to render)

Receptor activation: Growth factors bind RTKs (EGFR, TrkA/B)

RAS activation: SOS promotes RAS-GTP formation

RAF activation: RAS-GTP recruits and activates RAF

MEK activation: RAF phosphorylates MEK1/2 at activation loop

ERK activation: MEK phosphorylates ERK1/2 at Thr/Tyr

Downstream effects: ERK translocates to nucleus or acts on cytoplasmic targets

Synaptic Plasticity and Memory

MEK1-ERK signaling is a critical regulator of synaptic plasticity, the cellular basis of learning and memory[@ltp_synapse]:

Long-Term Potentiation (LTP)

Early LTP (E-LTP): MEK/ERK required for induction

Late LTP (L-LTP): Transcription and protein synthesis-dependent

NMDA receptor activation: Triggers MEK/ERK cascade

Calcium influx: Activates RAS-RAF-MEK pathway

Spatial Memory Formation

The hippocampus-dependent spatial memory formation relies critically on MEK/ERK signaling[@spatial_memory]:

Pattern separation/completion: ERK activation in CA3/dentate gyrus

Consolidation: ERK-dependent transcription in CA1

Retrieval: Reactivation of ERK during recall

Neurotrophin Signaling

MEK/ERK mediates effects of neurotrophins including BDNF and NGF[@growth_factor]:

Neuronal survival: ERK promotes pro-survival gene expression
Differentiation: ERK drives neuronal differentiation programs
Axon guidance: Growth cone responses mediated by MEK/ERK

Adult Neurogenesis

In the adult hippocampus, MEK/ERK signaling regulates neural stem cell function[@neurogenesis]:

Proliferation: ERK required for proliferation of neural progenitors
Differentiation: Promotes neuronal differentiation
Integration: ERK-dependent spine formation in new neurons

Role in Neurodegenerative Diseases

Alzheimer's Disease

AD is characterized by amyloid-β plaques, neurofibrillary tangles (hyperphosphorylated tau), and progressive cognitive decline. MEK/ERK signaling plays complex roles in AD pathogenesis[@ad_mapk]:

Tau Phosphorylation

ERK1/2 (activated by MEK1) can phosphorylate tau at multiple sites:

| Site | Kinase | Relevance |
|------|--------|------------|
| Thr181 | ERK1/2 | Early marker |
| Ser396 | ERK1/2 | Paired helical filament |
| Ser404 | ERK1/2 | Pathological |

Dysregulated ERK Signaling in AD

Amyloid-β effects: Aβ oligomers hyperactivate MEK/ERK

Tau pathology: ERK-mediated tau phosphorylation contributes to NFT formation

Synaptic dysfunction: Aberrant ERK signaling disrupts synaptic plasticity

Neuronal apoptosis: Chronic ERK activation can promote apoptosis

Parkinson's Disease

PD involves progressive loss of dopaminergic neurons in the substantia nigra pars compacta. MEK/ERK signaling has dual roles in PD[@pd_mapk]:

Neuroprotective Effects

Growth factor signaling: GDNF-mediated neuroprotection requires MEK/ERK

Anti-apoptotic signaling: ERK promotes survival gene expression

Mitochondrial function: ERK regulates mitochondrial dynamics

MEK Inhibitors in PD

Despite initial concerns, MEK inhibitors show promise in PD models[@neuroprotection]:

| Agent | Model | Effect |
|-------|-------|--------|
| Selumetinib | MPTP model | Neuroprotection |
| Trametinib | 6-OHDA model | Dopaminergic rescue |

Therapeutic Targeting

MEK Inhibitors in Clinical Use

Several MEK inhibitors are approved for cancer therapy:

| Drug | Indication | Notes |
|------|------------|-------|
| Trametinib (Mekinist) | Melanoma (BRAF V600E) | FDA approved |
| Cobimetinib (Cotellic) | Melanoma | FDA approved |
| Selumetinib (Koselugo) | Pediatric plexiform neurofibroma | FDA approved |

Challenges in Neurodegenerative Disease

While MEK inhibitors are well-established in oncology, CNS applications face challenges:

Blood-brain barrier penetration: Many inhibitors have limited CNS exposure

Chronic dosing: Cancer dosing differs from chronic neurodegeneration

Dose optimization: Balancing efficacy and toxicity

Cross-References

[MAP2K2 (MEK2) Gene](/genes/map2k2)
[ERK1 (MAPK3) Gene](/genes/mapl3)
[ERK2 (MAPK1) Gene](/genes/mapk1)
[RAF Kinases](/proteins/raf-kinases)

[MAPK Signaling Pathway](/mechanisms/mapk-signaling-neurodegeneration)
[Synaptic Plasticity](/mechanisms/synaptic-plasticity)
[Tau Phosphorylation](/mechanisms/tau-phosphorylation)
[Long-Term Potentiation](/mechanisms/ltp-mechanisms)

[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
[Neuropsychiatric Disorders](/diseases/neuropsychiatric-disorders)

Conclusions

MEK1 is a pivotal kinase in the MAPK/ERK signaling cascade with essential roles in neuronal function and viability. In the nervous system, MEK1-ERK signaling regulates synaptic plasticity, memory formation, tau phosphorylation, and cell survival. Dysregulated MEK signaling contributes to the pathogenesis of AD, PD, and other neurodegenerative conditions, though the precise role varies by disease and context.

References

[MEK1 inhibition ameliorates mitochondrial-dependent apoptosis induced by deltamethrin in mouse hippocampal neuron HT22 cells.](https://pubmed.ncbi.nlm.nih.gov/40058615/) (Toxicology in vitro : an international journal published in association with BIBRA, 2025, PMID:40058615)

[MicroRNA-16 targets mRNA involved in neurite extension and branching in hippocampal neurons during presymptomatic prion disease.](https://pubmed.ncbi.nlm.nih.gov/29277556/) (Neurobiology of disease, 2018, PMID:29277556)

[D1 dopamine receptor mediates dopamine-induced cytotoxicity via the ERK signal cascade.](https://pubmed.ncbi.nlm.nih.gov/15247297/) (The Journal of biological chemistry, 2004, PMID:15247297)

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MEK1 Protein

MEK1 Protein

MEK1 Protein

MEK1 Protein

Overview

Introduction

Structure and Molecular Architecture

Primary Structure

Domain Organization

Catalytic Mechanism

Normal Physiological Function

MAPK/ERK Cascade

Synaptic Plasticity and Memory

Long-Term Potentiation (LTP)

Spatial Memory Formation

Neurotrophin Signaling

Adult Neurogenesis

Role in Neurodegenerative Diseases

Alzheimer's Disease

Tau Phosphorylation

Dysregulated ERK Signaling in AD

Parkinson's Disease

Neuroprotective Effects

MEK Inhibitors in PD

Therapeutic Targeting

MEK Inhibitors in Clinical Use

Challenges in Neurodegenerative Disease

Cross-References

Related Proteins and Pathways

Related Mechanisms

Related Diseases

Conclusions

References