ITK, Tyrosine-protein kinase ITK/TSK
Enzyme Classification 220.127.116.11
Also Known as
ITK_HUMAN, ITK, EMT, LYK
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 (PubMed:12186560, PubMed:12682224, PubMed:21725281). Phosphorylates TBX21 at 'Tyr-530' and mediates its interaction with GATA3. Homooligomerizes; this association negatively regulates kinase activity (By similarity). Interacts with PPIA/CYPA; this interaction regulates TCR signal strength via a proline-directed conformational switch in ITK. Interacts with THEMIS (By similarity). Interacts with FASLG. Interacts with VAV1; this interaction is important for VAV1 localization and TCR-induced actin polarization. Interacts with TBX21.