EPHB3 (Eph Receptor B3) encodes a member of the Eph family of receptor tyrosine kinases. EPHB3 plays crucial roles in neural development, synaptic plasticity, cellular migration, and tissue boundary formation. Through binding to ephrin-B ligands, EPHB3 regulates dendritic spine morphology, synaptic function, and neural circuit formation. Dysregulated EPHB3 signaling has been implicated in Alzheimer's disease, Parkinson's disease, and various cancers[1].
| Attribute | Value |
|---|---|
| Gene Symbol | EPHB3 |
| Full Name | Eph Receptor B3 |
| Alternative Names | ETK2, HEK2, TYRO6 |
| Chromosomal Location | 3q27.1 |
| NCBI Gene ID | 2049 |
| Ensembl ID | ENSG00000149932 |
| UniProt ID | P54753 |
| OMIM | 601067 |
| Protein Class | Receptor tyrosine kinase |
| Associated Diseases | Alzheimer's disease, Parkinson's disease, Cancer |
The EPHB3 gene spans approximately 31 kb and consists of 19 exons. It encodes a protein of approximately 998 amino acids with a typical receptor tyrosine kinase architecture.
The EPHB3 receptor contains several distinct functional domains[2]:
Extracellular domain (1-400 aa) — Contains the ephrin-binding domain that recognizes ephrin-B ligands, a cysteine-rich region with conserved cysteine residues, and two fibronectin type III repeats that mediate protein-protein interactions and receptor clustering.
Transmembrane domain (400-430 aa) — A single-pass transmembrane helix that anchors the receptor in the plasma membrane and mediates ligand-dependent signaling.
Juxtamembrane region (430-460 aa) — Contains tyrosine residues that undergo autophosphorylation upon ligand binding, initiating downstream signaling cascades.
Tyrosine kinase domain (460-660 aa) — The intracellular catalytic domain with kinase activity that phosphorylates downstream substrates.
C-terminal tail (660-998 aa) — Contains binding sites for PDZ domain-containing proteins and other signaling adaptors.
EPHB3 functions as a bidirectional signaling receptor:
Upon ephrin-B binding, EPHB3 undergoes activation through several mechanisms[4]:
EPHB3 can also signal in reverse through ephrin-B ligands:
EPHB3 plays critical roles in development:
EPHB3 regulates synaptic properties:
EPHB3 is expressed in various brain regions:
Within neurons, EPHB3 localizes to:
Expression in hippocampus and cortex supports roles in learning and memory.
EPHB3 activity is regulated through:
EPHB3 binds primarily to:
The binding affinity and signaling outcomes vary depending on ligand specificity and cell context.
EPHB3 dysregulation is implicated in AD through multiple mechanisms[7]:
EPHB3 contributes to Alzheimer's disease through specific pathways:
EPHB3 contributes to PD through[9]:
EPHB3 is involved in tumor biology:
EPHB3 mediates unique bidirectional signaling:
Forward signaling:
Reverse signaling:
EPHB3 activates multiple signaling cascades:
EPHB3 affects synapses through:
EPHB3 interacts with multiple proteins:
| Interactor | Interaction Type | Function |
|---|---|---|
| Ephrin-B1/B2 | Ligand | Receptor activation |
| Grb2 | Adaptor | Signal transduction |
| Shc | Adaptor | MAPK pathway |
| PI3K | Effector | Survival signaling |
| FAK | Effector | Adhesion signaling |
| PSD-95 | Scaffold | Synaptic localization |
| SynGAP | Effector | Synaptic plasticity |
Klein R, et al. Eph/ephrin signaling in neural development and disease. Nature Reviews Neuroscience. 2009. ↩︎
Arvanitis DN, et al. EphB receptors and ephrin-B ligands in the nervous system. Cell and Tissue Research. 2020. ↩︎
Bjork S, et al. EPHB3 in neural circuit formation and plasticity. Developmental Neurobiology. 2020. ↩︎
Murai K, et al. Ephrin-B reverse signaling in synaptic development. Current Opinion in Neurobiology. 2021. ↩︎
Chen Y, et al. EPHB3 in synaptic plasticity and memory. Journal of Neuroscience. 2019. ↩︎
Xu M, et al. Role of EphB3 in microglial phagocytosis and neuroinflammation. Glia. 2022. ↩︎ ↩︎
Shen J, et al. EPHB3-mediated signaling in amyloid-beta toxicity. Molecular Neurodegeneration. 2021. ↩︎
Wang L, et al. EPHB3 and tau pathology in Alzheimer's disease models. Acta Neuropathologica. 2021. ↩︎
Liu X, et al. Eph/ephrin pathway in dopaminergic neuron development. Journal of Neurochemistry. 2022. ↩︎
Li H, et al. EphB3 as a therapeutic target in Parkinson's disease. npj Parkinson's Disease. 2023. ↩︎
Zhou R, et al. EphB3 signaling in axonal regeneration after injury. Journal of Neuroscience. 2021. ↩︎ ↩︎
Davis M, et al. EPHB3 mutations and neurodevelopmental disorders. Human Molecular Genetics. 2022. ↩︎
Zhang W, et al. Targeting EphB3 receptors for neuroprotection. Pharmacological Research. 2023. ↩︎