Activation of T cell Raf-1 at mitosis requires the protein-tyrosine kinase Lck.
The serine/threonine protein kinase Raf-1 is activated in response to a variety of growth factors in fibroblasts and hematopoietic cells. In T cells, Raf-1 is activated in response to stimulation through the T cell antigen receptor, the interleukin-2 receptor, and by stimulation of protein kinase C. We demonstrate here that in T cells, Raf-1 is also activated during mitosis. The mitotic activation of Raf-1 was not observed in the Lck-deficient cell line, J.CaM.1. During mitosis, Raf-1 was found to interact selectively with a mitotic form of Lck that migrated with a reduced electrophoretic mobility on SDS-polyacrylamide gels. We conclude that Raf-1 is activated during mitosis in T cells and that this mitotic activation of Raf-1 is dependent on the presence of Lck.
Pathan
N I
NI
Department of Biology, Purdue University, West Lafayette, Indiana 47907, USA.
Ashendel
C L
CL
Geahlen
R L
RL
Harrison
M L
ML
D000818:Animals; D004789:Enzyme Activation; D006801:Humans; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D046911:Macromolecular Substances; D051379:Mice; D008938:Mitosis; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D013601:T-Lymphocytes / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000378:metabolism*
D046911:Macromolecular Substances; D011518:Proto-Oncogene Proteins; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D019061:src-Family Kinases; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf