Tyrosyl phosphorylation and activation of MAP kinases by p56lck.
T cell signaling via the CD4 surface antigen is mediated by the associated tyrosyl protein kinase p56lck. The 42-kilodalton mitogen-activated protein (MAP) kinase (p42mapk) was tyrosyl-phosphorylated and activated after treatment of the murine T lymphoma cell line 171CD4+, which expresses CD4, with antibody to CD3. Treatment of the CD4-deficient cell line 171 with the same antibody did not result in phosphorylation or activation of p42mapk. Purified p56lck both tyrosyl-phosphorylated and stimulated the seryl-threonyl phosphotransferase activity of purified p44mpk, a MAP kinase isoform from sea star oocytes. A synthetic peptide modeled after the putative regulatory phosphorylation site in murine p42mapk (Tyr185) was phosphorylated by p56lck with a similar Vmax, but a fivefold lower Michaelis constant (Km) than a peptide containing the Tyr394 autophosphorylation site from p56lck. MAP kinases may participate in protein kinase cascades that link Src family protein-tyrosyl kinases to seryl-threonyl kinases such as those encoded by rsk and raf, which are putative substrates of MAP kinases.
Ettehadieh
E
E
Biomedical Research Centre, University of British Columbia, Vancouver, Canada.
Sanghera
J S
JS
Pelech
S L
SL
Hess-Bienz
D
D
Watts
J
J
Shastri
N
N
Aebersold
R
R
D000595:Amino Acid Sequence; D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology; D017252:CD3 Complex; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002460:Cell Line; D038362:Glycogen Synthase Kinase 3; D066298:In Vitro Techniques; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D016399:Lymphoma, T-Cell; D051379:Mice; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000502:physiology*; D010766:Phosphorylation; D011494:Protein Kinases / Q000502:physiology*; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D013601:T-Lymphocytes / Q000502:physiology
D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D009856:Oncogene Proteins, Viral; D011948:Receptors, Antigen, T-Cell; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D017871:Calcium-Calmodulin-Dependent Protein Kinases; D038362:Glycogen Synthase Kinase 3