Lck

Lck (or lymphocyte-specific protein tyrosine kinase) is a 56 kDa protein that is found inside specialized cells of the immune system called lymphocytes. Lck is a tyrosine kinase, which phosphorylates tyrosine residues of certain proteins involved in the intracellular signaling pathways of these lymphocytes. It is a member of the Src family of tyrosine kinases.

T cell signaling

Lck is most commonly found in T cells. It associates with the cytoplasmic tails of the CD4 and CD8 co-receptors on T helper cells and cytotoxic T cells, respectively, to assist signaling from the T cell receptor (TCR) complex. When the T cell receptor is engaged by the specific antigen presented by MHC, Lck acts to phosphorylate the intracellular chains of the CD3 and ζ-chains of the TCR complex, allowing another cytoplasmic tyrosine kinase called ZAP-70 to bind to them. Lck then phosphorylates and activates ZAP-70, which in turn phosphorylates another molecule in the signaling cascade called LAT (short for Linker of Activated T cells), a transmembrane protein that serves as a docking site for a number of other proteins, the most important of which are Shc-Grb2-SOS, PI3K, and phospholipase C (PLC). Additionally, upon T cell activation, a fraction of kinase active Lck, translocates from outside of lipid rafts (LR) to inside lipid rafts where it interacts with and activates LR-resident Fyn, which is involved in further downstream signaling activation.

LCK

LCK may refer to: