T-cell surface glycoprotein CD3 zeta chain (CD3ζ) (CD3ζ)

The T-cell surface glycoprotein CD3 zeta chain, encoded by the CD247 gene, is a fundamental transmembrane component of the T-cell receptor (TCR)-CD3 complex [2, 6]. It is distinguished by the presence of three immunoreceptor tyrosine-based activation motifs (ITAMs) in its cytoplasmic domain, which are essential for converting extracellular antigen recognition into intracellular signals [6, 20]. Upon TCR engagement, these ITAMs are phosphorylated by Src family kinases, such as Lck, which facilitates the recruitment and activation of ZAP-70 kinase [1, 20]. This process initiates critical downstream pathways that drive T-cell differentiation, proliferation, and the adaptive immune response [6, 10]. In modern immunotherapy, the CD3 zeta chain is the cornerstone of chimeric antigen receptor (CAR) design, providing the primary activation signal for FDA-approved therapies like Tisagenlecleucel and Axicabtagene ciloleucel [4, 17]. Reduced expression or dysfunction of this protein is a known mechanism of immune evasion in various cancers and chronic infections, making it a significant biomarker for immune competence [14, 16]. Additionally, genetic defects in the CD247 locus are associated with severe combined immunodeficiency and autoimmune conditions [10, 11].

Other names

CD247CD3ZT3ZTCRZCD3-ZETAT-cell receptor T3 zeta chainCluster of Differentiation 247CD247 molecule

The CD3 zeta chain functions as the primary signal transducer for the T-cell receptor complex. Upon antigen binding, its immunoreceptor tyrosine-based activation motifs (ITAMs) are phosphorylated by Lck and Fyn kinases, which creates docking sites for ZAP-70. This recruitment triggers downstream signaling cascades, including the PLC-gamma1 and Ras/MAPK pathways, leading to T-cell activation, cytokine secretion, and cytotoxic activity [1, 6, 20].