Zeta-chain-associated protein kinase 70 (ZAP-70) (ZAP-70)

Zeta-chain-associated protein kinase 70 (ZAP-70) is a 70 kDa cytoplasmic tyrosine kinase belonging to the Syk family, primarily expressed in T cells and natural killer (NK) cells (UniProt P43403). It is a fundamental component of the T-cell receptor (TCR) signaling pathway; upon TCR engagement, ZAP-70 is recruited to the phosphorylated immunoreceptor tyrosine-based activation motifs (ITAMs) of the CD3 zeta chain, where it is activated by Lck and subsequently phosphorylates adapter proteins like LAT and SLP-76 to propagate immune signals (PubMed: 15107456). In the context of Chronic Lymphocytic Leukemia (CLL), ZAP-70 mRNA and protein expression levels serve as critical prognostic biomarkers, where high expression is strongly associated with unmutated IGHV genes and a more aggressive clinical course (PubMed: 12730288). Mutations in the ZAP70 gene are linked to a form of autosomal recessive severe combined immunodeficiency (SCID) characterized by a selective lack of CD8+ T cells (PubMed: 7910231). While ZAP-70 is an attractive therapeutic target for autoimmune diseases and lymphoid malignancies, the development of highly selective small-molecule inhibitors is complicated by its structural similarity to the closely related Syk kinase (PubMed: 25133305). Current pharmacological efforts focus on dual Syk/ZAP-70 inhibition or the use of ZAP-70 mRNA levels to guide treatment intensity in leukemia patients.

Other names

ZAP7070 kDa zeta-associated proteinSyk-related tyrosine kinaseSRKSTDTZKZeta-chain-associated protein kinase 70 mRNA

Inhibition of the kinase domain to prevent phosphorylation of downstream substrates like LAT and SLP-76, thereby blocking T-cell receptor signaling.