A tyrosine-phosphorylated 110-120-kDa protein associates with the C-terminal SH2 domain of phosphotyrosine phosphatase-1D in T cell receptor-stimulated T cells.
The role of cytosolic phosphotyrosine phosphatases (PTPase) in T cell receptor (TCR)-mediated signaling was investigated. PTPase activity was detected in a purified immunocomplex comprising aggregated TCR from the cell surface of Jurkat T cells. Since TCR aggregation results in phosphorylation of critical immunoreceptor tyrosine-based activation motifs (ITAM) in the TCR zeta chain, a doubly tyrosine-phosphorylated synthetic peptide containing the membrane-proximal zeta chain ITAM (zeta p ITAM) was used to characterize TCR zeta-associated PTPases. PTPase activity was detected in stable association with zeta p ITAM and the SH2 domain-containing PTPase PTP-1D (Syp, SH-PTP2) was identified in this complex. TCR stimulation resulted in increased total PTPase activity and PTP-1D protein in zeta p ITAM precipitates. TCR stimulation did not result in the tyrosine phosphorylation of PTP-1D but caused the rapid and transient tyrosine phosphorylation of a 110-120-kDa protein which associated selectively with the C-terminal SH2 domain of PTP-1D. This currently unidentified phosphotyrosine protein may be involved in localizing PTP-1D to the TCR following receptor stimulation.
Frearson
J A
JA
Department of Immunology, The Babraham Institute, Cambridge, GB.
Yi
T
T
Alexander
D R
DR
D000595:Amino Acid Sequence; D000936:Antigen-Antibody Complex / Q000378:metabolism; D004789:Enzyme Activation / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010766:Phosphorylation; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism* / Q000494:pharmacology; D011940:Receptor Aggregation / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction / Q000276:immunology; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology* / Q000276:immunology; D014443:Tyrosine / Q000378:metabolism*; D018909:src Homology Domains
D000936:Antigen-Antibody Complex; D011948:Receptors, Antigen, T-Cell; D013438:Sulfhydryl Compounds; D014443:Tyrosine; D017027:Protein Tyrosine Phosphatases