Background：CD3epsilon is a 20 kD transmembrane protein, also known as CD3 or T3. It is a member of the Ig superfamily and primarily expressed on T cells, NK-T cells, and at different levels on thymocytes during T cell differentiation. CD3epsilon forms a TCR complex by associating with the CD3delta, gamma and ζ chains, as well as the TCR a/b or gamma/delta chains. CD3 plays a critical role in TCR signal transduction, T cell activation, and antigen recognition by binding the peptide/MHC antigen complex.
