Interleukin 2-induced protein phosphorylation/dephosphorylation in human non-adherent peripheral blood mononuclear cells: initial phosphorylation of two 75-kDa proteins.
The kinetics of protein phosphorylation/dephosphorylation induced by IL-2 in cells of the non-adherent subpopulation of human peripheral blood mononuclear cells after pretreatment with and without phytohaemagglutinin (PHA) was analyzed by two-dimensional gel electrophoresis. In cells not pretreated with PHA, IL-2 induced the phosphorylation of two 75-kDa proteins with pI values 6.6 and 6.9, detectable 30 min after addition of IL-2, and the dephosphorylation of a 94-kDa (pI 4.0) protein, two 85-kDa (pI 5.2 and 5.4) proteins and a 65-kDa (pI 4.9) protein. The latter three phosphoproteins were found to be unlabelled after PHA pretreatment, but upon IL-2 stimulation the 94-kDa and the 85-kDa proteins became labelled simultaneously with two minor phosphoproteins of 68 kDa (pI 5.7) and 37 kDa (pI 4.8). Moreover, PHA pretreatment of cells induced a drastic phosphorylation of a 48-kDa (pI 6.5) and a 46-kDa (pI 6.7) protein, which were gradually dephosphorylated after IL-2 addition. Phosphorylation of the 75-kDa proteins could not be detected when the cells were pretreated with PHA prior to labelling. These results suggest that IL-2-induced phosphorylation of the 75-kDa proteins is one of the early events in IL-2 stimulation, an event already completed in PHA-pretreated cells since PHA is known to induce release of IL-2. Furthermore, the retarded appearance of the labelled 75-kDa proteins suggests an IL-2-induced de novo synthesis, possibly reflecting the expression of the 75-kDa alpha chain of the IL-2 receptor.
Hamann
W
W
Friedrich-Miescher-Laboratorium der Max-Planck-Gesellschaft, Tübingen, F.R.G.
Anderer
F A
FA
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface / Q000032:analysis; D002460:Cell Line; D003601:Cytotoxicity Tests, Immunologic; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology*; D007526:Isoelectric Point; D008214:Lymphocytes / Q000378:metabolism*; D008970:Molecular Weight; D010766:Phosphorylation; D010835:Phytohemagglutinins / Q000378:metabolism; D011994:Recombinant Proteins; D013997:Time Factors; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D007376:Interleukin-2; D010835:Phytohemagglutinins; D011994:Recombinant Proteins