Definition of ZAP-70

ZAP-70: Zeta-chain-associated protein kinase 70. A member of the protein tyrosine kinase family, ZAP-70 is normally expressed in T cells and natural killer cells and has a critical role in the initiation of T-cell signaling. ZAP-70 is expressed in T cells and tumors of T-cell lineage. A high level of ZAP-70 expression appears restricted to T-cell proliferative diseases and a subgroup of chronic lymphocytic leukemia (CLL). The ZAP-70 gene is in chromosome 2q12.