FYN Gene — FYN Proto-Oncogene, Src Family Tyrosine Kinase <table class="infobox infobox-gene">Symbol </td>Full Name </td>Chromosomal Location </td>NCBI Gene ID </td>OMIM ID </td>Ensembl ID </td>UniProt ID </td>Protein Size </td>Molecular Weight </td>
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FYN Gene — FYN Proto-Oncogene, Src Family Tyrosine Kinase <table class="infobox infobox-gene">Symbol </td>Full Name </td>Chromosomal Location </td>NCBI Gene ID </td>OMIM ID </td>Ensembl ID </td>UniProt ID </td>Protein Size </td>Molecular Weight </td>
Pathway Diagram
Mermaid diagram (expand to render)
Introduction The FYN gene (FYN Proto-Oncogene, Src Family Tyrosine Kinase) encodes a member of the Src family of non-receptor tyrosine kinases (SFKs). FYN is a critical signaling molecule in the nervous system, playing essential roles in synaptic plasticity, learning and memory, [NMDA receptor](/entities/nmda-receptor) function, and myelin formation[@sala2000]. Dysregulation of FYN signaling is implicated in [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease-disease), schizophrenia, and multiple sclerosis.
Protein Structure FYN, like all Src family kinases, contains several conserved domains:
N-terminal myristoylation site : Targets FYN to the plasma membraneUnique domain : Confers specificity to each SFK memberSH3 domain : Proline-rich region bindingSH2 domain : Phosphotyrosine-containing motif bindingKinase domain : Catalytic tyrosine kinase activityFYN exists in two isoforms:
FYN-B : Full-length isoform, predominant in brainFYN-A : Alternatively spliced variant with different tissue distributionNormal Neuronal Function FYN plays multiple critical roles in the nervous system:
Synaptic Plasticity and Learning
NMDA Receptor Phosphorylation : FYN phosphorylates NR2A and NR2B subunits, modulating receptor functionPSD-95 Interaction : Forms signaling complexes at postsynaptic densities[Long-term Potentiation](/mechanisms/long-term-potentiation) (LTP) : Essential for LTP induction in hippocampal [neurons](/entities/neurons)Learning and Memory : FYN knockout mice show deficits in spatial memoryOligodendrocyte Development : Critical for proper myelinationNode of Ranvier Organization : Regulates sodium channel clusteringSignal Transduction
Receptor Tyrosine Kinase Signaling : Mediates responses to growth factorsIntegrin Signaling : Controls neuronal adhesion and migrationImmune Receptor Signaling : T-cell receptor signaling in [microglia](/cell-types/microglia-neuroinflammation)Expression Pattern FYN is expressed throughout the brain with highest levels in:
Cerebral [cortex](/brain-regions/cortex) (layers II-IV pyramidal neurons)[Hippocampus](/brain-regions/hippocampus) (CA1-CA3 pyramidal cells, dentate gyrus granule cells)Cerebellum (Purkinje cells)Basal ganglia (striatum, substantia nigra)Thalamus and hypothalamus Outside the brain, FYN is expressed in T-cells, NK cells, and other immune cells.
Disease Associations
Alzheimer's Disease FYN is centrally involved in AD pathogenesis[@kaufman2015]:
[Tau](/proteins/tau) Phosphorylation : FYN can phosphorylate tau at tyrosine residues, promoting pathologyNMDA Receptor Dysfunction : FYN-mediated phosphorylation contributes to excitotoxicity[Amyloid-beta](/proteins/amyloid-beta) Signaling : Aβ activates FYN, linking amyloid to downstream toxic signalingSynaptic Loss : FYN-dependent pathways contribute to synaptic impairmentTherapeutic Target : FYN inhibitors are being investigated for AD treatmentParkinson's Disease
Dopaminergic Signaling : FYN regulates dopamine receptor signaling[Alpha-synuclein](/proteins/alpha-synuclein) Phosphorylation : FYN can phosphorylate α-synuclein at Tyr125Neuroprotection : FYN activity is required for neuroprotective responsesSchizophrenia
NMDA Receptor Hypofunction : FYN deficiency may contribute to NMDA receptor dysfunctionCognitive Deficits : Linked to working memory impairmentsMultiple Sclerosis
Immune Cell Activation : FYN in T-cells contributes to autoimmune responsesDemyelination : Altered signaling in oligodendrocytesTherapeutic Targeting
Signaling Pathways FYN interacts with multiple signaling cascades:
PI3K/Akt Pathway : Downstream survival signalingMAPK/ERK Pathway : Growth and differentiationPLCγ Pathway : Calcium signalingSTAT Pathway : Transcriptional regulationResearch Highlights
FYN knockout mice display enhanced sensitivity to Aβ toxicity
Saracatinib (AZD0530) showed promise in AD clinical trials for cognitive symptoms
FYN gene variants are associated with schizophrenia risk
See Also
[PTK2B/PYK2](/proteins/ptk2b-protein)
[SRC Gene](/genes/src)
[NMDA Receptor Signaling](/mechanisms/nmda-receptor-signaling)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
[Tyrosine Kinase Signaling](/mechanisms/tyrosine-kinase-signaling)
[Synaptic Dysfunction Pathway](/mechanisms/synaptic-dysfunction-pathway)
External Links
[NCBI Gene: FYN](https://www.ncbi.nlm.nih.gov/gene/2534)
[UniProt: P39687](https://www.uniprot.org/uniprot/P39687)
[OMIM: 137025](https://www.omim.org/entry/137025)
[GeneCards: FYN](https://www.genecards.org/cgi-bin/carddisp.pl?gene=FYN)
References
[Sala C, et al., FYN and NMDA receptor-dependent synaptic plasticity (2000) (2000)](https://pubmed.ncbi.nlm.nih.gov/11027218/)
[Kaufman AC, et al., FYN kinase inhibition reduces Aβ toxicity (2015) (2015)](https://pubmed.ncbi.nlm.nih.gov/25988847/)
[Nygaard HB, et al., Targeting FYN in Alzheimer's disease (2018) (2018)](https://pubmed.ncbi.nlm.nih.gov/29330423/)
[Zhou X, et al., FYN in dopaminergic neuron survival (2016) (2016)](https://pubmed.ncbi.nlm.nih.gov/27013231/)
[Pearson M, et al., FYN structure and regulation (2011) (2011)](https://pubmed.ncbi.nlm.nih.gov/21881476/)
Pathway Diagram The following diagram shows the key molecular relationships involving FYN — FYN Proto-Oncogene, Src Family Tyrosine Kinase discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)
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