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CD3

CD3 has been classified into CD3γ, δ, ε and ζ chains. The sequence and structural homology of the human and mouse CD3γ, CD3δ and CD3ε genes, and their chromosomal proximity suggested that they arose by duplication of a common ancestral gene.

Glycosylation sites are present in the extracellular domain of the CD3γ and δ chains, but not in the extracellular domain of the ε chain.

The CD3γ, δ and ε chains are members of the immunoglobulin superfamily which have similarly positioned cysteine residues involved in disulfide bonds. The CD3γ, δ and ε chains possess the immunoreceptor tyrosine-based activation motif (ITAM), and in their cytoplasmic region an extracellular CXXCXE motif.