FYN

Proto-oncogene tyrosine-protein kinase Fyn is an is_associated_with::enzyme that in humans is encoded by the FYN is_associated_with::gene.

This gene is a member of the protein-tyrosine kinase is_associated_with::oncogene family. It encodes a membrane-associated tyrosine kinase that has been implicated in the control of cell growth. The protein associates with the p85 subunit of is_associated_with::phosphatidylinositol 3-kinase and interacts with the fyn-binding protein. Alternatively spliced transcript variants encoding distinct isoforms exist.

Function
Fyn is a protein, present in the signaling pathway of is_associated_with::integrins, which activates ras. Fyn is a tyrosine-specific phospho-transferase that is a member of the Src family of tyrosine protein kinases. Fyn is primarily localized to the cytoplasmic leaflet of the plasma membrane, where it phosphorylates tyrosine residues on key targets involved in a variety of different signaling pathways. Tyrosine phosphorylation of target proteins by Fyn serves to either regulate target protein activity, and/or to generate a binding site on the target protein that recruits other signaling molecules.

Role in signaling pathways
At least three tools have been useful in discerning a requirement for Fyn function in a particular signaling system:
 * cells derived from Fyn-/- mice (as well as cells derived from Fyn, Src, Yes, Fyn triple knockout mice (SYF));
 * a kinase-inactive, dominant negative mutant form of Fyn (K299M);
 * pharmacologic inhibitors of Src family kinases, such as PP2; note that PP2 also inhibits other tyrosine protein kinases such as Abl, PDGFR and c-Kit.

Using these tools, a requirement for Fyn has been shown for the following signaling pathways: T and is_associated_with::B cell receptor signaling, is_associated_with::integrin-mediated signaling, growth factor and is_associated_with::cytokine receptor signaling, platelet activation, is_associated_with::ion channel function, is_associated_with::cell adhesion, is_associated_with::axon guidance, fertilization, entry into is_associated_with::mitosis, and differentiation of natural killer cells, is_associated_with::oligodendrocytes and is_associated_with::keratinocytes.

Interactions
FYN has been shown to interact with:


 * is_associated_with::ADD2,
 * is_associated_with::BCAR1,
 * is_associated_with::C-Raf,
 * is_associated_with::CBLC,
 * is_associated_with::CD36,
 * is_associated_with::CD44,
 * CDH1,
 * is_associated_with::CHRNA7,
 * is_associated_with::CTNND1,
 * CBL,
 * CSF1R,
 * is_associated_with::DLG4,
 * is_associated_with::Dystroglycan,
 * is_associated_with::EPHA8,
 * is_associated_with::FYB,
 * FASLG,
 * is_associated_with::GNB2L1,
 * is_associated_with::GRIN2A,
 * ITK,
 * is_associated_with::Janus kinase 2,
 * is_associated_with::KHDRBS1,
 * is_associated_with::LKB1,
 * is_associated_with::Nephrin,
 * is_associated_with::PAG1,
 * is_associated_with::PIK3R2,
 * is_associated_with::PRKCQ,
 * is_associated_with::PTK2B,
 * is_associated_with::PTK2,
 * is_associated_with::PTPRT)
 * UNC119,
 * RICS,
 * is_associated_with::SH2D1A,
 * is_associated_with::SKAP1,
 * is_associated_with::Syk,
 * is_associated_with::TNK2,
 * is_associated_with::TRPC6,
 * is_associated_with::Tau protein,
 * is_associated_with::TrkB,
 * TYK2,
 * TUBA3C,
 * WAS,  and
 * is_associated_with::ZAP-70,