Human ZAP70 Antibody

ZAP70 (Zeta-associated protein 70 kDa; also Syk-related tyrosine kinase) is a 68-70 kDa member of the SYK subfamily, tyrosine kinase family of molecules. It is found in immature thymocytes, plus T cells and NK cells, and is essential for TCR-mediated IL-2 production, plus the development of CD8+ T cells. Human ZAP70 is 619 amino acids (aa) in length. It contains two SH2 domains (aa 10-102 and 162-254), a regulatory interdomain region (aa 255-337), and a C-terminal tyrosine kinase domain (aa 338-539). The two SH2 domains bind to phosphorylated tyrosines on the CD3  zeta -chain following TCR activation. This activates the ZAP70 kinase domain with the initiation of downstream signaling via SLP76 and LAT. There are four potential splice variants of ZAP70. One termed TZK is 37 kDa in size, and characterized by an alternative start site at Met308. This is expressed in very early thymocytes. Two others show an alternative start site 88 aa upstream of the standard site, with one of these variants also showing a deletion of aa 495-541. A fourth variant contains an eight aa substitution for aa 1-134. Over aa 10-102, human ZAP70 shares 98% aa identity with mouse ZAP70.