FYN - Tyrosine-protein kinase Fyn - human protein (Function)
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FYN »  Tyrosine-protein kinase Fyn   [ EC ]
Protein also known as:  Proto-oncogene c-Fyn.
Gene name:  FYN
Entry whose protein(s) existence is based on evidence at protein level
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Non-receptor tyrosine-protein kinase that plays a role in many biological processes including regulation of cell growth and survival, cell adhesion, integrin-mediated signaling, cytoskeletal remodeling, cell motility, immune response and axon guidance. Inactive FYN is phosphorylated on its C-terminal tail within the catalytic domain. Following activation by PKA, the protein subsequently associates with PTK2/FAK1, allowing PTK2/FAK1 phosphorylation, activation and targeting to focal adhesions. Involved in the regulation of cell adhesion and motility through phosphorylation of CTNNB1 (beta-catenin) and CTNND1 (delta-catenin). Regulates cytoskeletal remodeling by phosphorylating several proteins including the actin regulator WAS and the microtubule-associated proteins MAP2 and MAPT. Promotes cell survival by phosphorylating AGAP2/PIKE-A and preventing its apoptotic cleavage. Participates in signal transduction pathways that regulate the integrity of the glomerular slit diaphragm (an essential part of the glomerular filter of the kidney) by phosphorylating several slit diaphragm components including NPHS1, KIRREL and TRPC6. Plays a role in neural processes by phosphorylating DPYSL2, a multifunctional adapter protein within the central nervous system, ARHGAP32, a regulator for Rho family GTPases implicated in various neural functions, and SNCA, a small pre-synaptic protein. Participates in the downstream signaling pathways that lead to T-cell differentiation and proliferation following T-cell receptor (TCR) stimulation. Also participates in negative feedback regulation of TCR signaling through phosphorylation of PAG1, thereby promoting interaction between PAG1 and CSK and recruitment of CSK to lipid rafts. CSK maintains LCK and FYN in an inactive form. Promotes CD28-induced phosphorylation of VAV1.  
  • CuratedUniProtKB
GO molecular function 
ATP bindingdefinition[GO:0005524]  
  • IEAUniProtKB KW
CD4 receptor bindingdefinition[GO:0042609] silver  
  • IEAOrtholog Compara
CD8 receptor bindingdefinition[GO:0042610] silver  
  • IEAOrtholog Compara
Ephrin receptor bindingdefinition[GO:0046875]  
  • IPIUniProtKB
Glycoprotein bindingdefinition[GO:0001948]  
Growth factor receptor bindingdefinition[GO:0070851]  
  • IPIUniProtKB
Ion channel bindingdefinition[GO:0044325] silver  
  • IEAOrtholog Compara
Metal ion bindingdefinition[GO:0046872]  
  • IEAUniProtKB KW
Non-membrane spanning protein tyrosine kinase activitydefinition[GO:0004715]  
  • NASUniProtKB
Peptide hormone receptor bindingdefinition[GO:0051428] silver  
  • IEAOrtholog Compara
Phosphatidylinositol 3-kinase bindingdefinition[GO:0043548] silver  
  • IEAOrtholog Compara
Protein bindingdefinition[GO:0005515]  
  • IPIIntAct
  • IPIUniProtKB
T cell receptor bindingdefinition[GO:0042608] silver  
  • IEAOrtholog Compara
Tubulin bindingdefinition[GO:0015631] silver  
  • IEAOrtholog Compara
GO biological process 
Activated T cell proliferationdefinition[GO:0050798] silver  
  • IEAOrtholog Compara
Calcium ion transportdefinition[GO:0006816]  
  • NASUniProtKB
Cellular response to peptide hormone stimulusdefinition[GO:0071375] silver  
  • IEAOrtholog Compara
Dendrite morphogenesisdefinition[GO:0048813] silver  
  • IEAOrtholog Compara
Detection of mechanical stimulus involved in sensory perception of paindefinition[GO:0050966] silver  
  • IEAOrtholog Compara
Feeding behaviordefinition[GO:0007631]  
Forebrain developmentdefinition[GO:0030900] silver  
  • IEAOrtholog Compara
Intracellular signal transductiondefinition[GO:0035556]  
Negative regulation of extrinsic apoptotic signaling pathway in absence of liganddefinition[GO:2001240] silver  
  • IEAOrtholog Compara
Negative regulation of gene expressiondefinition[GO:0010629] silver  
  • IEAOrtholog Compara
Negative regulation of protein catabolic processdefinition[GO:0042177] silver  
  • IEAOrtholog Compara
Neuron migrationdefinition[GO:0001764] silver  
  • IEAOrtholog Compara
Peptidyl-tyrosine phosphorylationdefinition[GO:0018108] silver  
  • IEAOrtholog Compara
Positive regulation of neuron projection developmentdefinition[GO:0010976] silver  
  • IEAOrtholog Compara
Positive regulation of protein localization to nucleusdefinition[GO:1900182] silver  
  • IEAOrtholog Compara
Protein autophosphorylationdefinition[GO:0046777] silver  
  • IEAOrtholog Compara
Protein phosphorylationdefinition[GO:0006468]  
  • NASUniProtKB
Regulation of cell shapedefinition[GO:0008360] silver  
  • IEAOrtholog Compara
Response to drugdefinition[GO:0042493] silver  
  • IEAOrtholog Compara
Response to ethanoldefinition[GO:0045471] silver  
  • IEAOrtholog Compara
T cell receptor signaling pathwaydefinition[GO:0050852]  
  • IDAUniProtKB
Enzymatic activity 
This protein acts as an enzyme. It is known to catalyze the following reaction
EC ATP + a [protein]-L-tyrosine ADP + a [protein]-L-tyrosine phosphate.  
  • CuratedUniProtKB
It requires the following cofactor
  • CuratedUniProtKB
It is regulated in the following manner
Inhibited by phosphorylation of Tyr-531 by leukocyte common antigen and activated by dephosphorylation of this site.  
  • CuratedUniProtKB
More information is available from:
According to KEGG, this protein belongs to the following pathways:
Adherens junction  hsa04520+2534  
Axon guidance  hsa04360+2534  
Cholinergic synapse  hsa04725+2534  
Fc epsilon RI signaling pathway  hsa04664+2534  
Focal adhesion  hsa04510+2534  
Measles  hsa05162+2534  
Natural killer cell mediated cytotoxicity  hsa04650+2534  
Osteoclast differentiation  hsa04380+2534  
Pathogenic Escherichia coli infection  hsa05130+2534  
Prion diseases  hsa05020+2534  
T cell receptor signaling pathway  hsa04660+2534  
Viral myocarditis  hsa05416+2534  
According to Reactome, this protein belongs to the following pathways:
Antigen activates B Cell Receptor (BCR) leading to generation of second messengers  REACT_118700  
CD28 co-stimulation  REACT_19183  
CD28 dependent PI3K/Akt signaling  REACT_19358  
CD28 dependent Vav1 pathway  REACT_19238  
Cell surface interactions at the vascular wall  REACT_12051  
Constitutive PI3K/AKT Signaling in Cancer  REACT_147727  
CRMPs in Sema3A signaling  REACT_19199  
CTLA4 inhibitory signaling  REACT_19405  
DAP12 signaling  REACT_147814  
DCC mediated attractive signaling  REACT_22351  
FCGR activation  REACT_160274  
GPVI-mediated activation cascade  REACT_1695  
NCAM signaling for neurite out-growth  REACT_18334  
Nef and signal transduction  REACT_11068  
Nephrin interactions  REACT_23832  
Netrin mediated repulsion signals  REACT_22384  
PECAM1 interactions  REACT_12519  
PIP3 activates AKT signaling  REACT_75829  
Platelet Adhesion to exposed collagen  REACT_1230  
Regulation of KIT signaling  REACT_111225  
Regulation of signaling by CBL  REACT_23787  
Role of LAT2/NTAL/LAB on calcium mobilization  REACT_163769  
Sema3A PAK dependent Axon repulsion  REACT_19236  
SEMA3A-Plexin repulsion signaling by inhibiting Integrin adhesion  REACT_19279  
Signaling by ERBB2  REACT_115755  
Signaling by SCF-KIT  REACT_111040  


Biological process 
Adaptive immunity  definition   [KW-1064]
Host-virus interaction  definition   [KW-0945]
Immunity  definition   [KW-0391]
Molecular function 
Developmental protein  definition   [KW-0217]
Kinase  definition   [KW-0418]
Transferase  definition   [KW-0808]
Tyrosine-protein kinase  definition   [KW-0829]
Technical term 
Reference proteome  definition   [KW-1185]

Further external links

GeneWiki: FYN
GenomeRNAi: 2534
PRO: PR:P06241