Research ArticleImmunology

The kinase Itk and the adaptor TSAd change the specificity of the kinase Lck in T cells by promoting the phosphorylation of Tyr192

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Science Signaling  09 Dec 2014:
Vol. 7, Issue 355, pp. ra118
DOI: 10.1126/scisignal.2005384

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Switching Lck’s Attention

The Src family kinase (SFK) member Lck has distinct early and late functions in T cell signaling. Early after activation of the T cell receptor (TCR), Lck mediates signals close in space and time to the TCR; later, Lck regulates the actin cytoskeleton, reorganization of which is required for the stable interaction between T cells and antigen-presenting cells (APCs). Lck activity is determined by the balance in the phosphorylation status of two tyrosine residues, one activating and the other inhibitory. Granum et al. identified a third tyrosine residue, Tyr192, which was phosphorylated in response to TCR stimulation. T cells expressing a mutant Lck lacking this tyrosine failed to form stable interactions with APCs. Lck phosphorylated at Tyr192 preferentially associated with regulators of the actin cytoskeleton. Thus, phosphorylation of Tyr192 in Lck enables Lck to switch its attention from the TCR to the actin cytoskeleton, thereby fulfilling different functions at different stages of T cell activation.

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