title: Transphosphorylation of Bruton's tyrosine kinase on tyrosine 551 is critical for B cell antigen receptor function.
abstract: Bruton's tyrosine kinase (Btk) is required for B cell development and B cell antigen receptor (BCR) function. Cross-linking of BCR induces phosphorylation of Btk at Tyr551 and Tyr223. However, the functional requirement of these phosphorylation for BCR signaling remains unclear. We demonstrate here that mutation of Tyr551, not Tyr223, abrogates the BCR-induced calcium mobilization. Not only Lyn, but also Syk was required for tyrosine phosphorylation of Btk in BCR signaling. These results suggest that transphosphorylation of Btk on Tyr551 is essential for BCR function and that this phosphorylation is mediated through the concerted actions of Lyn and Syk.
authors.affiliation: Department of Molecular Genetics, Institute for Liver Research, Kansai Medical University, Moriguchi 570, Japan. kurosaki@mxr.meshnet.or.jp
authors.forename: T
authors.initials: T
authors.lastname: Kurosaki
authors.forename: M
authors.initials: M
authors.lastname: Kurosaki
mesh_terms: D000077329:Agammaglobulinaemia Tyrosine Kinase; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002645:Chickens; D004792:Enzyme Precursors / Q000235:genetics / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D015398:Signal Transduction; D000072377:Syk Kinase; D014443:Tyrosine / Q000378:metabolism*; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D011947:Receptors, Antigen, B-Cell; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D000077329:Agammaglobulinaemia Tyrosine Kinase; D000072377:Syk Kinase; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D002118:Calcium