Structural highlights
Function
[ITK_MOUSE] Tyrosine kinase that plays an essential role in regulation of the adaptive immune response. Regulates the development, function and differentiation of conventional T-cells and nonconventional NKT-cells. When antigen presenting cells (APC) activate T-cell receptor (TCR), a series of phosphorylation lead to the recruitment of ITK to the cell membrane, in the vicinity of the stimulated TCR receptor, where it is phosphorylated by LCK. Phosphorylation leads to ITK autophosphorylation and full activation. Once activated, phosphorylates PLCG1, leading to the activation of this lipase and subsequent cleavage of its substrates. In turn, the endoplasmic reticulum releases calcium in the cytoplasm and the nuclear activator of activated T-cells (NFAT) translocates into the nucleus to perform its transcriptional duty. Phosphorylates 2 essential adapter proteins: the linker for activation of T-cells/LAT protein and LCP2. Then, a large number of signaling molecules such as VAV1 are recruited and ultimately lead to lymphokine production, T-cell proliferation and differentiation.[1]
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
We report here the NMR-derived structure of the binary complex formed by the interleukin-2 tyrosine kinase (Itk) Src homology 3 (SH3) and Src homology 2 (SH2) domains. The interaction is independent of both a phosphotyrosine motif and a proline-rich sequence, the classical targets of the SH2 and SH3 domains, respectively. The Itk SH3/SH2 structure reveals the molecular details of this nonclassical interaction and provides a clear picture for how the previously described prolyl cis/trans isomerization present in the Itk SH2 domain mediates SH3 binding. The higher-affinity cis SH2 conformer is preorganized to form a hydrophobic interface with the SH3 domain. The structure also provides insight into how autophosphorylation in the Itk SH3 domain might increase the affinity of the intermolecular SH3/SH2 interaction. Finally, we can compare this Itk complex with other examples of SH3 and SH2 domains engaging their ligands in a nonclassical manner. These small binding domains exhibit a surprising level of diversity in their binding repertoires.
Proline isomerization preorganizes the Itk SH2 domain for binding to the Itk SH3 domain.,Severin A, Joseph RE, Boyken S, Fulton DB, Andreotti AH J Mol Biol. 2009 Apr 3;387(3):726-43. Epub 2009 Feb 12. PMID:19361414[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Qi Q, Xia M, Bai Y, Yu S, Cantorna M, August A. Interleukin-2-inducible T cell kinase (Itk) network edge dependence for the maturation of iNKT cell. J Biol Chem. 2011 Jan 7;286(1):138-46. doi: 10.1074/jbc.M110.148205. Epub 2010, Oct 29. PMID:21036902 doi:http://dx.doi.org/10.1074/jbc.M110.148205
- ↑ Severin A, Joseph RE, Boyken S, Fulton DB, Andreotti AH. Proline isomerization preorganizes the Itk SH2 domain for binding to the Itk SH3 domain. J Mol Biol. 2009 Apr 3;387(3):726-43. Epub 2009 Feb 12. PMID:19361414 doi:http://dx.doi.org/10.1016/j.jmb.2009.02.012
