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Activation and internalization of p56 lck upon CD45 triggering of Jurkat cells
Author(s) -
MarieCardine Anne,
MaridonneauParini Isabelle,
Fischer Siegmund
Publication year - 1994
Publication title -
european journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 201
eISSN - 1521-4141
pISSN - 0014-2980
DOI - 10.1002/eji.1830240603
Subject(s) - internalization , jurkat cells , immunoprecipitation , biology , kinase , dephosphorylation , microbiology and biotechnology , endocytosis , phosphorylation , phosphatase , t cell , biochemistry , receptor , antibody , immune system , immunology
Abstract Relationships between CD45 and p56 Ick have been suggested by co‐immunoprecipitation of both proteins and by dephosphorylation of the p56 lck regulatory site, Tyr 505, by CD45 in vitro . We investigated whether the kinase activity of p56 lck is modulated in T cells triggered via CD45. We showed that incubation of Jurkat cells with a combination of two anti‐CD45 monoclonal antibodies (mAb) (MC5/2 + D3/9) induced an increase in p56 lck kinase activity, while a single mAb did not. Under these conditions, p56 lck underwent two consecutive waves of activation. This was accompanied by internalization of the kinase and by a time‐dependent increased accessibility of CD45 phosphatase at the plasma membrane. Similarly, activation and internalization of p56 lck were observed using a combination of anti‐CD45 (MC5/2) and anti‐CD2(T11 2 ) mAb, suggesting that a functional complex consisting of CD45, CD2 and p56 lck was formed upon cell triggering. Taken together, these results suggests that: (i) CD45 participates in the regulation of p56 lck kinase activity in vivo and that (ii) CD45 could play a mediator role in the stimulation and endocytosis of p56 lck through the CD2 pathway.