Biochemical analysis of the CD45-p56(lck) complex in Jurkat T cells lacking expression of lymphocyte phosphatase-associated phosphoprotein.

@article{Bruyns1998BiochemicalAO,
  title={Biochemical analysis of the CD45-p56(lck) complex in Jurkat T cells lacking expression of lymphocyte phosphatase-associated phosphoprotein.},
  author={Eddy Bruyns and Henning Kirchgessner and Stefan C. Meuer and Burkhart Schraven},
  journal={International immunology},
  year={1998},
  volume={10 2},
  pages={
          185-94
        }
}
In human and mouse lymphocytes the protein tyrosine phosphatase CD45, a key molecule involved in T cell activation, non-covalently associates with the tyrosine kinase p56(lck) and lymphocyte phosphatase-associated phosphoprotein (LPAP), a 32 kDa phosphoprotein of unknown function. In order to gain insight into the function of LPAP we have generated an LPAP-deficient Jurkat variant by means of antisense strategies. Analysis of the CD45-p56(lck) molecular complex in this cell line revealed that… 
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1 CD 45-associated protein inhibits CD 45 dimerization and upregulates its protein tyrosine phosphatase activity Running head : CD 45-AP INHIBITS CD 45 DIMERIZATION
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The results support a model in which binding of CD45-AP to inactive CD45 dimers converts them to active monomers, as well as using microsomal fractions from both mouse thymocytes and ALST-1 transfectants, which support this model.
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Lymphnodes from LPAP‐null mice showed increased cellularity, which could indicate that expression of LPAP might be required to prevent expansion of lymphocytes in particular lymphatic organs rather than potentiating immune responses.
In vivo disruption of T cell development by expression of a dominant‐negative polypeptide designed to abolish the SLP‐76/Gads interaction
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The ability of this polypeptide to inhibit TCR‐induced integrin activity in Jurkat cells and to inhibit in vivo thymocyte development and primary T cell function is investigated to provide evidence for the in vivo function of a dominant‐negative peptide based upon the biology of SLP‐76 action and suggest the possibility of therapeutic potential of targeting the SLp‐76/Gads interaction.
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