CD3E

CD3E, the CD3ε subunit of the T-cell receptor complex, is a glycoprotein expressed on the surface of T-cells and encoded by the CD3E gene.CD3E is part of the T-cell receptor (TCR) signalling complex and binds non-covalently to the TCRαβ or TCRγδ subunits. The mechanism of action is that upon recognition and binding of the T-cell receptor to antigenic peptides presented by the major histocompatibility complex (MHC), CD3E, in concert with other CD3 molecules, transmits an activation signal that leads to the activation of T cells. The signalling pathway involves the activation of tyrosine kinases, such as ζ-chain-associated protein kinase 76 (ZAP-70), which in turn activates a variety of downstream signalling molecules, including phosphatidylinositol 3-kinase (PI3K), protein kinase C (PKC), and mitogen-activated protein kinase (MAPK). These signalling pathways ultimately lead to the development of T cell proliferation, differentiation and effector functions.

Biologically, CD3E is essential for T cell-mediated immune responses, and is involved in regulating the activation of cytotoxic T cells and helper T cells, which are important for the clearance of pathogens, antitumour immunity, and the modulation of autoimmune responses.Abnormalities in the function of CD3E may be associated with certain immune deficiencies and autoimmune diseases.