ZAP70 is a 70-kD tyrosine phosphoprotein that associates with the zeta chain and undergoes tyrosine phosphorylation following TCR stimulation. The ZAP70 gene is expressed in T- and natural KILLER cells. Protein-Tyrosine Kinases (PTKs) play an integral role in T-cell activation. Stimulation of the T-cell antigen receptor results in tyrosine phosphorylation of a number of cellular substrates. One of these is the TCR-zeta chain, which can mediate the transduction of extracellular stimuli into cellular effector functions Salomon AR, et al. (2003) Proc Natl Acad Sci U S A, 100(2): 443-448 Ku GM, et al. (2001) EMBO J, 20(3): 457-465 Tang J, et al. (1999) Proc Natl Acad Sci U S A, 96(17): 9775-9780 Zhao Q, et al. (1996) Mol Cell Biol, 16(12): 6765-6774 Williams BL, et al. (1999) EMBO J, 18(7): 1832-1844 Adjali O, et al. (2005) J Clin Invest, 115(8): 2287-2295.
