B lymphocyte activation is accompanied by phosphorylation of a 72-kDa protein-tyrosine kinase.
The cross-linking of membrane IgM on the surface of splenic B lymphocytes or WEHI 231 cells leads to the rapid phosphorylation on tyrosine of a 72-kDa protein as detected in Western blotting experiments using anti-phosphotyrosine antibodies. The 72-kDa phosphoprotein detected in this manner comigrates, in both one- and two-dimensional polyacrylamide gel electrophoresis systems, with PTK72, a 72-kDa protein-tyrosine kinase characterized previously in this laboratory (Zioncheck, T. F., Harrison, M. L., Isaacson, C. C., and Geahlen, R. L. (1988) J. Biol. Chem. 263, 19195-19202). Anti-phosphotyrosine antibodies and anti-PTK72 antibodies immunoprecipitate the same protein-tyrosine kinase from extracts of anti-IgM-activated cells as determined by immune complex kinase assays and one-dimensional phosphopeptide mapping. These results indicate that the tyrosine phosphorylation of a 72-kDa protein-tyrosine kinase is an early event in the activation of B lymphocytes via the antigen receptor.
Hutchcroft
J E
JE
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
Harrison
M L
ML
Geahlen
R L
RL
D000818:Animals; D001402:B-Lymphocytes / Q000502:physiology*; D015153:Blotting, Western; D002846:Chromatography, Affinity; D003432:Cross-Linking Reagents; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D007075:Immunoglobulin M / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000276:immunology / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
D003432:Cross-Linking Reagents; D007075:Immunoglobulin M; D010750:Phosphoproteins; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases