Intimate association of Thy-1 and the T-cell antigen receptor with the CD45 tyrosine phosphatase.
Immunoprecipitation of Thy-1 from Triton X-100 detergent lysates of surface-iodinated and chemically cross-linked T cells precipitated at least five major and discrete bands. Four of these bands were identified as Thy-1, CD45 (a transmembrane tyrosine phosphatase), a major histocompatibility complex-encoded class I molecule, and beta 2-microglobulin. Similar analyses revealed that CD45 was coprecipitated from lysates of cross-linker-treated cells by antibodies to the T-cell antigen receptor (TCR). The same pattern of coprecipitated bands was observed when digitonin was used to lyse untreated cells. Immunoprecipitation of Thy-1 or the TCR from lysates of cross-linked T cells precipitated CD45 tyrosine phosphatase activity. Calculations based upon the amounts of coprecipitated enzymatic activity or TCR zeta chain indicate that a substantial fraction of Thy-1 and TCR complexes can be cross-linked to CD45. These data support a model in which the dependence of Thy-1 signaling on TCR coexpression is due to their common interaction with a tyrosine phosphatase and provide a possible structural basis for the influence of CD45 on TCR-mediated signaling.
Volarević
S
S
Biological Response Modifiers Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
Burns
C M
CM
Sussman
J J
JJ
Ashwell
J D
JD
D000818:Animals; D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation / Q000302:isolation & purification*; D000954:Antigens, Surface / Q000302:isolation & purification*; D002462:Cell Membrane / Q000201:enzymology / Q000276:immunology; D003432:Cross-Linking Reagents; D004591:Electrophoresis, Polyacrylamide Gel; D006649:Histocompatibility Antigens / Q000302:isolation & purification*; D007700:Kinetics; D017493:Leukocyte Common Antigens; D008562:Membrane Glycoproteins / Q000302:isolation & purification*; D051379:Mice; D008809:Mice, Inbred C3H; D010749:Phosphoprotein Phosphatases / Q000302:isolation & purification* / Q000378:metabolism; D011485:Protein Binding; D017027:Protein Tyrosine Phosphatases; D011948:Receptors, Antigen, T-Cell / Q000302:isolation & purification*; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology*; D018800:Thy-1 Antigens
D000911:Antibodies, Monoclonal; D000943:Antigens, Differentiation; D000954:Antigens, Surface; D003432:Cross-Linking Reagents; D006649:Histocompatibility Antigens; D008562:Membrane Glycoproteins; D011948:Receptors, Antigen, T-Cell; D018800:Thy-1 Antigens; D010749:Phosphoprotein Phosphatases; D017493:Leukocyte Common Antigens; D017027:Protein Tyrosine Phosphatases