CD3e molecule, epsilon also known as CD3E. The protein is the CD3-epsilon polypeptide, which together with CD3-gamma, -delta and -zeta, and the T-cell receptor alpha/beta and gamma/delta heterodimers, forms the T cell receptor-CD3 complex. This complex plays an important role in coupling antigen recognition to several intracellular signal-transduction pathways. The epsilon polypeptide plays an essential role in T-cell development. Defects in this gene cause severe immunodeficiency. This gene has also been linked to a susceptibility to type I diabetes in women. T-cell surface glycoprotein CD3 epsilon chain has been shown to interact with TOP2B, CD3EAP and NCK2.