The catalytic activity of Src-family tyrosine kinase is required for B cell antigen receptor signaling.
The Src family protein-tyrosine kinases (PTKs) are known to be important for B cell antigen receptor (BCR) signaling. To study the mechanism of action of Src-PTK in BCR signaling, kinase deficient- and Src homology 2 (SH2)-mutants of Src-PTK were transfected into Lyn-deficient B cells and analyzed. Kinase activity of Src-PTK was essential for tyrosine phosphorylation of Syk and calcium mobilization upon receptor ligation, whereas these events were not affected by the mutation of SH2 domain. Receptor-mediated tyrosine phosphorylation of Lyn was still observed in Syk-deficient B cells. These results demonstrate that the BCR-induced phosphorylation of Src-PTK is independent of Syk and that the kinase activity of Src-PTK is critical for BCR signaling.
Takata
M
M
Department of Oncology and Immunology, Wyeth-Ayerst Research, Pearl River, NY 10965, USA.
Kurosaki
T
T
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002384:Catalysis; D002478:Cells, Cultured; D002645:Chickens; D007163:Immunosorbent Techniques; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000235:genetics / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000502:physiology*; D015398:Signal Transduction; D014162:Transfection; D018909:src Homology Domains
D011947:Receptors, Antigen, B-Cell; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src); D002118:Calcium