ERK2 (Extracellular Signal-Regulated Kinase 2), also known as MAPK1 (Mitogen-Activated Protein Kinase 1) or p42 MAP Kinase, is a serine/threonine protein kinase that serves as a central mediator of intracellular signal transduction. As the second major isoform in the MAPK/ERK cascade, ERK2 plays essential roles in regulating cell proliferation, differentiation, survival, apoptosis, and synaptic plasticity 1. While closely related to ERK1, ERK2 has distinct and non-redundant functions, with ERK2 knockout being embryonic lethal in mice, highlighting its critical importance 2. [1]
ERK2 is ubiquitously expressed and responds to a wide variety of extracellular stimuli including growth factors, neurotransmitters, hormones, and stress. In the brain, ERK2 is particularly important for synaptic plasticity, learning, memory, and neuronal development. Dysregulation of ERK2 signaling is implicated in numerous neurological disorders including Alzheimer's disease, Parkinson's disease, and depression 3. [2]
| Protein Name | Extracellular Signal-Regulated Kinase 2 |
|---|---|
| Gene | [MAPK1](/genes/mapk1) |
| UniProt ID | [P28482](https://www.uniprot.org/uniprot/P28482) |
| PDB IDs | 1GOL, 2ERK, 4QTB, 4QTC |
| Molecular Weight | ~42 kDa |
| Subcellular Localization | Cytoplasm, nucleus |
| Protein Family | MAP kinase family |
| Expression | Ubiquitous, highest in brain, heart, lung |
ERK2 contains the canonical MAP kinase fold with distinct functional regions 4:
N-terminal Region (residues 1-100): Contains the common docking (CD) domain that mediates interactions with upstream activators, phosphatases, and substrates.
Kinase Domain (residues 101-358): The catalytic core containing the activation loop with key regulatory phosphorylation sites (T185, Y187).
C-terminal Region (residues 359-360): Short tail with nuclear localization and export signals.
ERK2 is activated through dual phosphorylation by MEK1/2:
The phosphorylated, active ERK2 can then translocate to the nucleus and phosphorylate various transcription factors and other nuclear targets.
The crystal structure of ERK2 has been solved in both active and inactive conformations, revealing the molecular basis for kinase activation and substrate recognition 5.
ERK2 is activated by diverse extracellular signals through receptor-mediated pathways:
Receptor tyrosine kinases:
G-protein coupled receptors:
Other stimuli:
Growth Factor → RTK → Grb2/Sos → Ras → Raf (MEKKK) → MEK1/2 (MAPKK) → ERK1/2 (MAPK)
This conserved cascade provides signal amplification:
Activated ERK2 phosphorylates over 200 known substrates 6:
Transcription factors:
Kinases:
Other nuclear targets:
Cytosolic targets:
In the nervous system, ERK2 is crucial for 3:
Synaptic plasticity:
Learning and memory:
Neuronal development:
ERK2 regulates numerous cellular functions:
ERK2 signaling is significantly altered in Alzheimer's disease 7:
Pathological changes:
Role in pathogenesis:
Therapeutic implications:
ERK2 in Parkinson's disease 8:
ERK2 signaling in Huntington's disease 9:
ERK2 activation in cerebral ischemia:
ERK2 in mood disorders:
Targeting ERK2 therapeutically is complex:
| Approach | Agent/Mechanism | Stage | Notes |
|---|---|---|---|
| MEK inhibitors | Trametinib, Cobimetinib | FDA approved (cancer) | Prevent ERK activation |
| ERK inhibitors | SCH772984 | Preclinical | Direct ERK1/2 inhibition |
| Modulators | Various compounds | Research | Context-specific targeting |
Oncology:
Neurology:
The MAPK1 gene is located on chromosome 22q11.21 and consists of 10 exons.
Polymorphisms:
ERK2 is ubiquitously expressed:
ERK2 interacts with numerous signaling networks:
While structurally similar, ERK1 and ERK2 have distinct functions 2:
| Feature | ERK2 | ERK1 |
|---|---|---|
| Size | 42 kDa | 44 kDa |
| Phosphorylation sites | T185, Y187 | T202, Y204 |
| Expression | Higher overall | Lower overall |
| Knockout phenotype | Embryonic lethal | Viable, mild phenotype |
| Substrate specificity | Some unique targets | Some unique targets |
ERK2 is a pivotal kinase in cellular signal transduction with critical roles in normal brain function and neurodegenerative disease pathogenesis. Its essential nature is highlighted by the embryonic lethal phenotype of ERK2 knockout mice. While therapeutic targeting of ERK2 is complicated by its ubiquitous expression and dual roles, ongoing research continues to identify context-specific vulnerabilities that may be exploited for treating neurological disorders. Understanding the precise roles of ERK2 in different cellular contexts remains an important area of investigation.
Johnson and Lapadat, Mitogen-activated protein kinase pathways (2002). Science. 2002. ↩︎
Raman et al. Molecular mechanisms of ERK activation (2007). Journal of Biological Chemistry. 2007. ↩︎