The T cell antigen receptor (TCR) recognizesforeign antigens and translates such recognition eventsinto intracellularsignalsthat elicit a change in the cell froma dormant to an activated state.Much of this signaling processcan be attributed to a multisubunitcomplex of proteins that associates directly with the TCR. Thiscomplex has been designated CD3 (cluster of differentiation 3). It iscomposed of five invariant polypeptide chainsthat associate to form three dimers: a heterodimer of γ and ε chains(γε), a heterodimer of δ and ε chains(δε) and a homodimer of two ζ chains(ζζ) or a heterodimer of ζ and η chains(ζη). The ζ and η chains are encoded bythe same gene but differ in theircarboxyl-terminal ends due to an alternative splicing event. The γ, ε and δ chains each contain a single copy of a conserved immunoreceptor tyrosine-based activationmotif (ITAM). In contrast, the ζ chain containsthree consecutive copies of the same motif. Phosphorylated ITAMs act as docking sitesfor protein kinases such as ZAP-70 and Syk and are also capable of regulating theirkinase activity. The crystalstructure of ZAP-70’s SH2 domains bound to the ζ chain ITAMs has been solved.
应用类型
WB
免疫原
A synthetic peptide corresponding to residues in Human CD3G.
