ZAP-70 (Zeta-chain-associated protein kinase 70) is a protein normally expressed near the surface membrane of T cells and natural killer cells. It is part of the T cell receptor, and plays a critical role in T-cell signaling. Its molecular weight is 70 kDa, and it is a member of the protein-tyrosine kinase family.
ZAP-70 in B cells is used as a prognostic marker in identifying different forms of chronic lymphocytic leukemia (CLL). DNA analysis has distinguished two major types of CLL, with different survival times. CLL that is positive for the marker ZAP-70 has an average survival of 8 years. CLL that is negative for ZAP-70 has an average survival of more than 25 years. Many patients, especially older ones, with slowly progressing disease can be reassured and may not need any treatment in their lifetimes.
T lymphocytes are activated by engagement of the T cell receptor with processed antigen fragments presented by professional antigen presenting cells (i.e. macrophages, dendritic cells and B cells) via the MHC. Upon this activation, the TCR co-receptor CD4 or CD8 binds to the MHC, activating the co-receptor associated tyrosine kinase Lck. Lck phosphorylates the intracellular portions of the CD3 complex (called ITAMs), creating a docking site for ZAP-70. The most important member of the CD3 family is CD3-zeta, to which ZAP-70 binds (hence the abbreviation). The tandem SH2-domains of ZAP-70 are engaged by the doubly phosphorylated ITAMs of CD3-zeta, which positions ZAP-70 to phosphorylate the transmembrane protein linker of activated T cells (LAT). Phosphorylated LAT, in turn, serves as a docking site to which a number of signaling proteins bind including SLP-76. The final outcome of T cell activation is the transcription of several gene products which allow the T cells to differentiate, proliferate and secrete a number of cytokines.
^Lupher ML, Reedquist KA, Miyake S, Langdon WY, Band H (Sep 1996). "A novel phosphotyrosine-binding domain in the N-terminal transforming region of Cbl interacts directly and selectively with ZAP-70 in T cells". The Journal of Biological Chemistry. 271 (39): 24063–8. doi:10.1074/jbc.271.39.24063. PMID8798643.
^Meng W, Sawasdikosol S, Burakoff SJ, Eck MJ (Mar 1999). "Structure of the amino-terminal domain of Cbl complexed to its binding site on ZAP-70 kinase". Nature. 398 (6722): 84–90. doi:10.1038/18050. PMID10078535.
^Han J, Kori R, Shui JW, Chen YR, Yao Z, Tan TH (Dec 2003). "The SH3 domain-containing adaptor HIP-55 mediates c-Jun N-terminal kinase activation in T cell receptor signaling". The Journal of Biological Chemistry. 278 (52): 52195–202. doi:10.1074/jbc.M305026200. PMID14557276.
^Pelosi M, Di Bartolo V, Mounier V, Mège D, Pascussi JM, Dufour E, Blondel A, Acuto O (May 1999). "Tyrosine 319 in the interdomain B of ZAP-70 is a binding site for the Src homology 2 domain of Lck". The Journal of Biological Chemistry. 274 (20): 14229–37. doi:10.1074/jbc.274.20.14229. PMID10318843.
^Perez-Villar JJ, Whitney GS, Sitnick MT, Dunn RJ, Venkatesan S, O'Day K, Schieven GL, Lin TA, Kanner SB (Aug 2002). "Phosphorylation of the linker for activation of T-cells by Itk promotes recruitment of Vav". Biochemistry. 41 (34): 10732–40. doi:10.1021/bi025554o. PMID12186560.
^Pacini S, Ulivieri C, Di Somma MM, Isacchi A, Lanfrancone L, Pelicci PG, Telford JL, Baldari CT (Aug 1998). "Tyrosine 474 of ZAP-70 is required for association with the Shc adaptor and for T-cell antigen receptor-dependent gene activation". The Journal of Biological Chemistry. 273 (32): 20487–93. doi:10.1074/jbc.273.32.20487. PMID9685404.
Deindl S, Kadlecek TA, Brdicka T, Cao X, Weiss A, Kuriyan J (May 2007). "Structural basis for the inhibition of tyrosine kinase activity of ZAP-70". Cell. 129 (4): 735–46. doi:10.1016/j.cell.2007.03.039. PMID17512407.
Nel AE, Gupta S, Lee L, Ledbetter JA, Kanner SB (Aug 1995). "Ligation of the T-cell antigen receptor (TCR) induces association of hSos1, ZAP-70, phospholipase C-gamma 1, and other phosphoproteins with Grb2 and the zeta-chain of the TCR". The Journal of Biological Chemistry. 270 (31): 18428–36. doi:10.1074/jbc.270.31.18428. PMID7629168.
Negishi I, Motoyama N, Nakayama K, Nakayama K, Senju S, Hatakeyama S, Zhang Q, Chan AC, Loh DY (Aug 1995). "Essential role for ZAP-70 in both positive and negative selection of thymocytes". Nature. 376 (6539): 435–8. doi:10.1038/376435a0. PMID7630421.
Mustelin T, Williams S, Tailor P, Couture C, Zenner G, Burn P, Ashwell JD, Altman A (Apr 1995). "Regulation of the p70zap tyrosine protein kinase in T cells by the CD45 phosphotyrosine phosphatase". European Journal of Immunology. 25 (4): 942–6. doi:10.1002/eji.1830250413. PMID7737297.
Katzav S, Sutherland M, Packham G, Yi T, Weiss A (Dec 1994). "The protein tyrosine kinase ZAP-70 can associate with the SH2 domain of proto-Vav". The Journal of Biological Chemistry. 269 (51): 32579–85. PMID7798261.
Schumann G, Dasgupta JD (Sep 1994). "Specificity of signal transduction through CD16, TCR-CD3 and BCR receptor chains containing the tyrosine-associated activation motif". International Immunology. 6 (9): 1383–92. doi:10.1093/intimm/6.9.1383. PMID7819147.
Watts JD, Affolter M, Krebs DL, Wange RL, Samelson LE, Aebersold R (Nov 1994). "Identification by electrospray ionization mass spectrometry of the sites of tyrosine phosphorylation induced in activated Jurkat T cells on the protein tyrosine kinase ZAP-70". The Journal of Biological Chemistry. 269 (47): 29520–9. PMID7961936.
Ku G, Malissen B, Mattei MG (1994). "Chromosomal location of the Syk and ZAP-70 tyrosine kinase genes in mice and humans". Immunogenetics. 40 (4): 300–2. doi:10.1007/BF00189976. PMID8082894.
Chan AC, van Oers NS, Tran A, Turka L, Law CL, Ryan JC, Clark EA, Weiss A (May 1994). "Differential expression of ZAP-70 and Syk protein tyrosine kinases, and the role of this family of protein tyrosine kinases in TCR signaling". Journal of Immunology. 152 (10): 4758–66. PMID8176201.
Elder ME, Lin D, Clever J, Chan AC, Hope TJ, Weiss A, Parslow TG (Jun 1994). "Human severe combined immunodeficiency due to a defect in ZAP-70, a T cell tyrosine kinase". Science. 264 (5165): 1596–9. doi:10.1126/science.8202712. PMID8202712.
Chan AC, Kadlecek TA, Elder ME, Filipovich AH, Kuo WL, Iwashima M, Parslow TG, Weiss A (Jun 1994). "ZAP-70 deficiency in an autosomal recessive form of severe combined immunodeficiency". Science. 264 (5165): 1599–601. doi:10.1126/science.8202713. PMID8202713.
Wange RL, Malek SN, Desiderio S, Samelson LE (Sep 1993). "Tandem SH2 domains of ZAP-70 bind to T cell antigen receptor zeta and CD3 epsilon from activated Jurkat T cells". The Journal of Biological Chemistry. 268 (26): 19797–801. PMID8366117.
Huby RD, Carlile GW, Ley SC (Dec 1995). "Interactions between the protein-tyrosine kinase ZAP-70, the proto-oncoprotein Vav, and tubulin in Jurkat T cells". The Journal of Biological Chemistry. 270 (51): 30241–4. doi:10.1074/jbc.270.51.30241. PMID8530437.
Plas DR, Johnson R, Pingel JT, Matthews RJ, Dalton M, Roy G, Chan AC, Thomas ML (May 1996). "Direct regulation of ZAP-70 by SHP-1 in T cell antigen receptor signaling". Science. 272 (5265): 1173–6. doi:10.1126/science.272.5265.1173. PMID8638162.
Bubeck Wardenburg J, Fu C, Jackman JK, Flotow H, Wilkinson SE, Williams DH, Johnson R, Kong G, Chan AC, Findell PR (Aug 1996). "Phosphorylation of SLP-76 by the ZAP-70 protein-tyrosine kinase is required for T-cell receptor function". The Journal of Biological Chemistry. 271 (33): 19641–4. doi:10.1074/jbc.271.33.19641. PMID8702662.