Fyn tyrosine kinase

Fyn is a nonreceptor tyrosine kinase related to Src that is frequently found in cell junctions. Die protein is N-myristoylated and palmitoylated and thereby becomes associated with caveolae-like membrane microdomains. Fyn can interact with a variety of other signaling molecules and control a diversity of biological processes such as T cell receptor signaling, regulation of brain function, and adhesion mediated signaling. 

An inhibitory phosphorylation of the tyrosine kinases Lck and Fyn is also important for signal transduction, and this is performed by Csk kinase. This phosphorylation takes place at the C-terminus of Lck and inhibits the kinase activity in a similar way to that already structurally illustrated for Src kinase (see 8.3.2). 

In addition to the Lck kinase, other tyrosine kinases are activated on ligand binding to the IL-2 receptor. These are Fyn kinase and the Janus kinases Jakl and Jak3. 

Fig. 16.11. Model of the association of Fyn kinase with the NMDA receptor The NMDA receptor is shown as a tetramer of NRl and NR2 subunits. The C-terminal tail of NR2 interacts with PDZ2 of PSD-95. The protein tyrosine kinase Fyn is assumed to bind to PDZ3 of PSD-95 via its SH2 domain. Fyn also is anchored to the ceU membrane via its myristoylated N-terminus. GK guanylate kinase domain of PSD-95. According to Sala and Sheng (1999), with permission.

Mulhern, T. D., Shaw, G. L., Morton, C. J., Day, A. J., and Campbell, I. D. (1997). The SH2 domain from the tyrosine kinase Fyn in complex with a phosphotyrosyl peptide reveals insights into domain stability and binding specificity. Structure 5, 1313-1323. 

Kapp, K., Schubler, P., Kunz, W. and Grevelding, C.G. (2001) Identification, isolation and characterization of a Fyn-like tyrosine kinase from Schistosoma mansoni. Parasitology 1 22, 31 7-327. 

Ilangumaran, S., Ami, S., van Echten-Deckert, G., Borisch, B., and Hoessli, D. C. (1999). Microdomain-dependent regulation of Lck and Fyn protein-tyrosine kinases in T lymphocyte plasma membranes. Mol. Biol. Cell 10(4), 891-905. 

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