Abstract
The gene encoding Bruton tyrosine kinase (Btk) is known to be mutated in human X chromosome-linked agammaglobulinemia and in the Xid mouse. This kinase was examined in B lymphocytes before and after antigen receptor ligation and also in pre-B cells. Btk was found to be catalytically activated and tyrosine phosphorylated in response to anti-IgM stimulation in B cells. This kinase is also constitutively phosphorylated on tyrosine residues in pre-B cells. These findings point to a functional role for Btk in pre-antigen and antigen receptor signaling during B-cell development and provide a biochemical explanation for the X-linked genetic syndromes already linked to this kinase.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Agammaglobulinaemia Tyrosine Kinase
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Agammaglobulinemia / genetics
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Agammaglobulinemia / immunology
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Animals
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B-Lymphocytes / enzymology*
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B-Lymphocytes / immunology
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Cell Line
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Enzyme Activation
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Hematopoietic Stem Cells / enzymology
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Hematopoietic Stem Cells / immunology
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Humans
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Immunoglobulin M
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Kinetics
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Mice
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Mice, Mutant Strains
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Models, Biological
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Mutation
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Phosphorylation
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Phosphotyrosine
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Protein-Tyrosine Kinases / isolation & purification
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Protein-Tyrosine Kinases / metabolism*
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Receptors, Antigen, T-Cell / metabolism*
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Signal Transduction
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Tyrosine / analogs & derivatives
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Tyrosine / analysis
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X Chromosome
Substances
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Immunoglobulin M
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Receptors, Antigen, T-Cell
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Phosphotyrosine
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Tyrosine
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Protein-Tyrosine Kinases
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Agammaglobulinaemia Tyrosine Kinase
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BTK protein, human
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Btk protein, mouse