CD45 tyrosine phosphatase-activated p59fyn couples the T cell antigen receptor to pathways of diacylglycerol production, protein kinase C activation and calcium influx

EMBO J. 1992 Dec;11(13):4887-97.


The role of the CD45 phosphotyrosine phosphatase in coupling the T cell antigen receptor complex (TCR) to intracellular signals was investigated. CD45- HPB-ALL T cells were transfected with cDNA encoding the CD45RA+B+C- isoform. The tyrosine kinase activity of p59fyn was found to be 65% less in CD45- cells than in CD45+ cells, whereas p56lck kinase activity was comparable in both sub-clones. In CD45- cells the TCR was uncoupled from protein tyrosine phosphorylation, phospholipase C gamma 1 regulation, inositol phosphate production, calcium signals, diacylglycerol production and protein kinase C activation. Restoration of TCR coupling to all these pathways correlated with the increased p59fyn activity observed in CD45-transfected cells. Co-aggregation of CD4- or CD8-p56lck kinase with the TCR in CD45- cells restored TCR-induced protein tyrosine phosphorylation, phospholipase C gamma 1 regulation and calcium signals. Receptor-mediated calcium signals were largely due (60-90%) to Ca2+ influx, and only a minor component (10-40%) was caused by Ca2+ release from intracellular stores. Maximal CD3-mediated Ca2+ influx occurred at CD3 mAb concentrations at which inositol phosphate production was non-detectable. These results indicate that CD45-regulated p59fyn plays a critical role in coupling the TCR to specific intracellular signalling pathways and that CD4- or CD8-p56lck can only restore signal transduction coupling in CD45- cells when brought into close association with the TCR.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport
  • Blotting, Western
  • Calcium / metabolism*
  • Diglycerides / biosynthesis*
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Activation
  • Humans
  • Inositol Phosphates / biosynthesis
  • Leukocyte Common Antigens / physiology*
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
  • Phosphorylation
  • Precipitin Tests
  • Protein Kinase C / metabolism*
  • Protein Tyrosine Phosphatases / physiology*
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-fyn
  • Receptors, Antigen, T-Cell / metabolism*
  • Tumor Cells, Cultured


  • Diglycerides
  • Inositol Phosphates
  • Proto-Oncogene Proteins
  • Receptors, Antigen, T-Cell
  • Protein-Tyrosine Kinases
  • FYN protein, human
  • Lymphocyte Specific Protein Tyrosine Kinase p56(lck)
  • Proto-Oncogene Proteins c-fyn
  • Protein Kinase C
  • Leukocyte Common Antigens
  • Protein Tyrosine Phosphatases
  • Calcium