| Structural highlights
Disease
[LCK_HUMAN] Severe combined immunodeficiency due to LCK deficiency. Note=A chromosomal aberration involving LCK is found in leukemias. Translocation t(1;7)(p34;q34) with TCRB.
Function
[LCK_HUMAN] Non-receptor tyrosine-protein kinase that plays an essential role in the selection and maturation of developing T-cells in the thymus and in the function of mature T-cells. Plays a key role in T-cell antigen receptor (TCR)-linked signal transduction pathways. Constitutively associated with the cytoplasmic portions of the CD4 and CD8 surface receptors. Association of the TCR with a peptide antigen-bound MHC complex facilitates the interaction of CD4 and CD8 with MHC class II and class I molecules, respectively, thereby recruiting the associated LCK protein to the vicinity of the TCR/CD3 complex. LCK then phosphorylates tyrosines residues within the immunoreceptor tyrosine-based activation motifs (ITAM) of the cytoplasmic tails of the TCR-gamma chains and CD3 subunits, initiating the TCR/CD3 signaling pathway. Once stimulated, the TCR recruits the tyrosine kinase ZAP70, that becomes phosphorylated and activated by LCK. Following this, a large number of signaling molecules are recruited, ultimately leading to lymphokine production. LCK also contributes to signaling by other receptor molecules. Associates directly with the cytoplasmic tail of CD2, which leads to hyperphosphorylation and activation of LCK. Also plays a role in the IL2 receptor-linked signaling pathway that controls the T-cell proliferative response. Binding of IL2 to its receptor results in increased activity of LCK. Is expressed at all stages of thymocyte development and is required for the regulation of maturation events that are governed by both pre-TCR and mature alpha beta TCR. Phosphorylates other substrates including RUNX3, PTK2B/PYK2, the microtubule-associated protein MAPT, RHOH or TYROBP.[1] [2] [3] [4] [5] [6]
Publication Abstract from PubMed
The binding of Src-homology 2 (SH2) domains to phosphotyrosine (pY) sites is critical for the autoinhibition and substrate recognition of the eight Src family kinases (SFKs). The high sequence conservation of the 120 human SH2 domains poses a significant challenge to selectively perturb the interactions of even the SFK SH2 family against the rest of the SH2 domains. We have developed synthetic binding proteins, termed monobodies, for six of the SFK SH2 domains with nanomolar affinity. Most of these monobodies competed with pY ligand binding and showed strong selectivity for either the SrcA (Yes, Src, Fyn, Fgr) or SrcB subgroup (Lck, Lyn, Blk, Hck). Interactome analysis of intracellularly expressed monobodies revealed that they bind SFKs but no other SH2-containing proteins. Three crystal structures of monobody-SH2 complexes unveiled different and only partly overlapping binding modes, which rationalized the observed selectivity and enabled structure-based mutagenesis to modulate inhibition mode and selectivity. In line with the critical roles of SFK SH2 domains in kinase autoinhibition and T-cell receptor signaling, monobodies binding the Src and Hck SH2 domains selectively activated respective recombinant kinases, whereas an Lck SH2-binding monobody inhibited proximal signaling events downstream of the T-cell receptor complex. Our results show that SFK SH2 domains can be targeted with unprecedented potency and selectivity using monobodies. They are excellent tools for dissecting SFK functions in normal development and signaling, as well as to interfere with aberrant SFK signaling networks in cancer cells.
Selective Targeting of SH2 Domain-Phosphotyrosine Interactions of Src Family Tyrosine Kinases with Monobodies.,Kukenshoner T, Schmit NE, Bouda E, Sha F, Pojer F, Koide A, Seeliger M, Koide S, Hantschel O J Mol Biol. 2017 Mar 24. pii: S0022-2836(17)30139-0. doi:, 10.1016/j.jmb.2017.03.023. PMID:28347651[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Gelkop S, Gish GD, Babichev Y, Pawson T, Isakov N. T cell activation-induced CrkII binding to the Zap70 protein tyrosine kinase is mediated by Lck-dependent phosphorylation of Zap70 tyrosine 315. J Immunol. 2005 Dec 15;175(12):8123-32. PMID:16339550
- ↑ Mason LH, Willette-Brown J, Taylor LS, McVicar DW. Regulation of Ly49D/DAP12 signal transduction by Src-family kinases and CD45. J Immunol. 2006 Jun 1;176(11):6615-23. PMID:16709819
- ↑ Goh YM, Cinghu S, Hong ET, Lee YS, Kim JH, Jang JW, Li YH, Chi XZ, Lee KS, Wee H, Ito Y, Oh BC, Bae SC. Src kinase phosphorylates RUNX3 at tyrosine residues and localizes the protein in the cytoplasm. J Biol Chem. 2010 Mar 26;285(13):10122-9. doi: 10.1074/jbc.M109.071381. Epub 2010, Jan 25. PMID:20100835 doi:10.1074/jbc.M109.071381
- ↑ Collins M, Tremblay M, Chapman N, Curtiss M, Rothman PB, Houtman JC. The T cell receptor-mediated phosphorylation of Pyk2 tyrosines 402 and 580 occurs via a distinct mechanism than other receptor systems. J Leukoc Biol. 2009 Dec 22. PMID:20028775 doi:jlb.0409227
- ↑ Wang H, Zeng X, Fan Z, Lim B. RhoH modulates pre-TCR and TCR signalling by regulating LCK. Cell Signal. 2011 Jan;23(1):249-58. doi: 10.1016/j.cellsig.2010.09.009. Epub 2010, Sep 16. PMID:20851766 doi:10.1016/j.cellsig.2010.09.009
- ↑ Scales TM, Derkinderen P, Leung KY, Byers HL, Ward MA, Price C, Bird IN, Perera T, Kellie S, Williamson R, Anderton BH, Reynolds CH. Tyrosine phosphorylation of tau by the SRC family kinases lck and fyn. Mol Neurodegener. 2011 Jan 26;6:12. doi: 10.1186/1750-1326-6-12. PMID:21269457 doi:10.1186/1750-1326-6-12
- ↑ Kukenshoner T, Schmit NE, Bouda E, Sha F, Pojer F, Koide A, Seeliger M, Koide S, Hantschel O. Selective Targeting of SH2 Domain-Phosphotyrosine Interactions of Src Family Tyrosine Kinases with Monobodies. J Mol Biol. 2017 Mar 24. pii: S0022-2836(17)30139-0. doi:, 10.1016/j.jmb.2017.03.023. PMID:28347651 doi:http://dx.doi.org/10.1016/j.jmb.2017.03.023
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