CD3 epsilon chain of the T cell receptor complex (CD3E)

The **CD3 epsilon chain** is a transmembrane protein that forms part of the T cell receptor (TCR)–CD3 complex, a multi-subunit receptor critical for T cell development and function[2][6][7][8]. CD3 epsilon partners with CD3 gamma and delta to form the CD3 complex’s heterodimers and, together with zeta chains and the TCR alpha/beta heterodimer, constitutes the integral TCR-CD3 signal transduction module[2][4][6]. Engagement of the TCR complex by antigen–MHC triggers phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) in CD3 cytoplasmic domains, initiating the intracellular signaling cascade crucial for T cell activation and immune response[7][8]. Genetic deficiency of CD3 epsilon causes severe immunodeficiency, underscoring its essential role in adaptive immunity[6]. The molecule is also a therapeutic target for monoclonal antibodies used in transplantation, autoimmune disease, and certain cancers[3][7].

Other names

CD3 epsilonCD3-epsilonCD3eT-cell surface glycoprotein CD3 epsilon chain

Antibody-mediated activation or blockade of T cell receptor signaling - Depletion of T cells - Induction of T cell anergy or tolerance