CD3 Complex

**Semantic type:** Amino Acid, Peptide, or Protein

**Definition:** A protein complex comprised of one T-cell surface glycoprotein CD3 delta chain (CD3D), one T-cell surface glycoprotein CD3 gamma chain (CD3G) and two T-cell surface glycoprotein CD3 epsilon chains (CD3E). CD3D, CD3G and CD3E are transmembrane proteins with one extracellular immunoglobulin domain and one intracellular ITAM domain. The CD3 complex is a T-cell co-receptor that noncovalently associates with either the disulfide bound heterodimeric alpha/beta T-cell receptor (TCR) or gamma/delta TCR and two copies of the accessory protein, T-cell surface glycoprotein CD3 zeta chain (CD247), which is a transmembrane protein with three ITAM domains. The TCR moiety of the TCR-CD3 complex binds to MHC and processed antigens on antigen presenting cells, which triggers phosphorylation of and cellular propagation of the signal by CD247 and the CD3 complex.

**Synonyms:** - CD3 - CD3 - CD3 - T-Cell Surface Glycoprotein CD3 - T3 Complex