FYN
Description
The FYN (FYN proto-oncogene, Src family tyrosine kinase) is a protein-coding gene located on chromosome 6.
Proto-oncogene tyrosine-protein kinase Fyn (p59-FYN, Slk, Syn, MGC45350, Gene ID 2534) is an enzyme that in humans is encoded by the FYN gene. Fyn is a 59-kDa member of the Src family of kinases typically associated with T-cell and neuronal signaling in development and normal cell physiology. Disruptions in these signaling pathways often have implications in the formation of a variety of cancers. By definition as a proto-oncogene, Fyn codes for proteins that help regulate cell growth. Changes in its DNA sequence transform it into an oncogene that leads to the formation of a different protein with implications for normal cell regulation. Fyn is a member of the protein-tyrosine kinase 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 phosphatidylinositol 3-kinase and interacts with the fyn-binding protein. Alternatively spliced transcript variants encoding distinct isoforms exist.
== History == Fyn is a member of the Src-family of kinases (SFK), the first proto-oncogene to be identified.
FYN is a 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. It is involved in the regulation of cell adhesion and motility through phosphorylation of CTNNB1 (beta-catenin) and CTNND1 (delta-catenin). It regulates cytoskeletal remodeling by phosphorylating several proteins, including the actin regulator WAS and the microtubule-associated proteins MAP2 and MAPT. FYN promotes cell survival by phosphorylating AGAP2/PIKE-A and preventing its apoptotic cleavage. It 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, KIRREL1, and TRPC6. FYN 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. It participates in the downstream signaling pathways that lead to T-cell differentiation and proliferation following T-cell receptor (TCR) stimulation. FYN phosphorylates PTK2B/PYK2 in response to T-cell receptor activation. It 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. FYN promotes CD28-induced phosphorylation of VAV1. In mast cells, it phosphorylates CLNK after activation of immunoglobulin epsilon receptor signaling.
FYN is also known as SLK, SYN, p59-FYN.
