title: Phosphorylation of the N-terminal and C-terminal CD3-epsilon-ITAM tyrosines is differentially regulated in T cells.
abstract: Tyrosine phosphorylation of immunoreceptor tyrosine-based activation motifs (ITAMs) within CD3 chains is crucial for the recruitment of protein tyrosine kinases and effector molecules into the T cell receptor. Thus, phenylalanine substitution at the N-terminal tyrosine residue of the CD3-epsilon-ITAM abolished signal transduction functions of this ITAM, including phosphorylation at the C-terminal ITAM tyrosine, and its association with ZAP-70. In contrast, mutation at the C-terminal tyrosine of CD3-epsilon-ITAM did not prevent phosphorylation at the N-terminal tyrosine, nor its association with Lck, or p85 PI 3-K regulatory subunit. In contrast to the ZAP-70/diphosphorylated CD8-epsilon-ITAM interaction, the Lck/monophosphorylated CD8-epsilon-ITAM interaction was sensitive to octylglucoside, an agent that disrupts Lck interaction with membrane rafts. Therefore, association of Lck with membrane rafts seems to be essential for stabilization of Lck/CD3-epsilon protein-protein interactions. Overall, the data suggest that the sequential and coordinated phosphorylation of CD3-epsilon-ITAM tyrosines provides to CD3-epsilon the potential to interact with multiple downstream effectors and signaling pathways.
authors.affiliation: Instituto de Parasitología y Biomedicina, Consejo Superior de Investigaciones Científicas, Granada, 18001, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Guirado
authors.forename: Isabel
authors.initials: I
authors.lastname: de Aós
authors.forename: Teresa
authors.initials: T
authors.lastname: Orta
authors.forename: Luis
authors.initials: L
authors.lastname: Rivas
authors.forename: Cox
authors.initials: C
authors.lastname: Terhorst
authors.forename: Mercedes
authors.initials: M
authors.lastname: Zubiaur
authors.forename: Jaime
authors.initials: J
authors.lastname: Sancho
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D017252:CD3 Complex; D019556:COS Cells; D005960:Glucosides / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D021962:Membrane Microdomains / Q000187:drug effects; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D017252:CD3 Complex; C115335:CD3E protein, human; D005960:Glucosides; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; D019000:Phosphotyrosine; C018619:octyl-beta-D-glucoside; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human