A protein kinase C inhibitory activity is present in the human T lymphoblast cell line Jurkat.
The human lymphoblast cell line Jurkat is widely used as a model system for studying signal transduction pathways during lymphocyte activation. We report the presence of a potent endogenous inhibitor of protein kinase C (PKC) in the cytosolic fraction of Jurkat cells. This inhibitor is not diffusible and is thermolabile; it is assumed to be a protein. It was separated from PKC by ion-exchange chromatography on DEAE-cellulose. The inhibitory activity was partially reversed by increasing the concentration of the PKC substrate; increasing that of PKC activators (calcium and phospholipids) was without effect. PKC activity was inhibited by more than 90% in the crude cytosolic fraction but the inhibition could be completely reversed by diluting the cell extract. This inhibitory activity could not be detected in the cytosol from normal lymphocytes or from lymphoblasts from leukemic patients.
Laboratoire de Biochimie, INSERM U75, Faculté de Médecine  Necker-Enfants Malades, Paris, France.
S
S
Columelli
A M
AM
Houllier
J L
JL
Pérignon
D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology; D017252:CD3 Complex; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry*; D006801:Humans; D008213:Lymphocyte Activation; D009363:Neoplasm Proteins / Q000302:isolation & purification / Q000494:pharmacology*; D014411:Neoplastic Stem Cells / Q000737:chemistry*; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000473:pathology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D015398:Signal Transduction; D006377:T-Lymphocytes, Helper-Inducer / Q000737:chemistry*; D014407:Tumor Cells, Cultured / Q000737:chemistry
D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D009363:Neoplasm Proteins; D011948:Receptors, Antigen, T-Cell; D011493:Protein Kinase C