Antigen-bearing MHC Class II: TCR with phosphorylated ITAMs:CD4 ZAP-70 bound to phosphorylated ITAM motifs Recruitment of ZAP-70 to phosphorylated ITAMs Authored: Rudd, C.E., de Bono, B, Garapati, P V, 2008-01-24 15:53:10 Phosphorylation of the ITAMs by Lck is followed by the recruitment of the ZAP-70 a member of Syk family PTK, to the receptor complex. ZAP-70 is exclusively expressed in T cells and NK cells. The dually phosphorylated ITAMs provide a high-affinity docking site for the tandem SH2-domains of the ZAP-70. Once recruited, ZAP-70 is activated by phosphorylation and will be responsible for the phosphorylation of further downstream molecules. Due to the presence of 10 ITAMs in the TCR complex, up to 10 ZAP-70 molecules may cluster on the fully phosphorylated receptors. Pubmed12485116 Pubmed8520027 Pubmed9850860 Reactome Database ID Release 43202344 Reactome, http://www.reactome.org ReactomeREACT_12642 Reviewed: Trowsdale, J, 2008-02-26 12:02:59