Complexing of the CD-3 subunit by a monoclonal antibody activates a microtubule-associated protein 2 (MAP-2) serine kinase in Jurkat cells.
Treatment of Jurkat T-cells with anti-CD-3 monoclonal antibodies resulted in the rapid and transient activation of a serine kinase which utilized the microtubule-associated protein, MAP-2, as a substrate in vitro. The kinase was also activated on treatment of Jurkat cells with phytohaemagglutinin, but with a different time course. The activation of the MAP-2 kinase by anti-CD-3 antibodies was dose-dependent, with maximal activity observed at concentrations of greater than 500 ng/ml. Normal human E-rosette-positive T-cells also exhibited induction of MAP-2 kinase activity during anti-CD-3 treatment. The enzyme was optimally active in the presence of 2 mM-Mn2+; lower levels of activity were observed with Mg2+, even at concentrations up to 20 mM. The kinase was partially purified by passage over DE-52 Sephacel with the activity eluting as a single peak at 0.25 M-NaCl. The molecular mass was estimated to be 45 kDa by gel filtration. The activation of the MAP-2 kinase was probably due to phosphorylation of this enzyme as treatment with alkaline phosphatase diminished its activity. These data demonstrate that the stimulation of T-cells through the CD-3 complex results in the activation of a novel serine kinase which may be critically involved in signal transduction in these cells.
Hanekom
C
C
Department of Internal Medicine, Stellenbosch University Medical School, Cape Town, Republic of South Africa.
Nel
A
A
Gittinger
C
C
Rheeder
A
A
Landreth
G
G
D000911:Antibodies, Monoclonal / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D017252:CD3 Complex; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D004306:Dose-Response Relationship, Immunologic; D004789:Enzyme Activation; D004790:Enzyme Induction; D006801:Humans; D008562:Membrane Glycoproteins / Q000276:immunology; D011494:Protein Kinases / Q000096:biosynthesis / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000201:enzymology* / Q000276:immunology
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D008562:Membrane Glycoproteins; D011948:Receptors, Antigen, T-Cell; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases