The recognition of cognate antigenic
peptide in the context of major
histocompatibility complex (peptide-
MHC) by the TCR is thought to induce
conformational changes within the
associated CD3 chains that facilitate their
phosphorylation and association with
downstream proteins (Alarcon et al.,
2003). The CD3 δ-, γ-, ε- and ζ-chains all
contain immunoreceptor tyrosine-based
activation motifs (ITAMs), which are
phosphorylated by the Src kinase
leukocyte-specific tyrosine kinase (Lck)