Bruton's tyrosine kinase (Btk) plays critical roles in B cell development and activation. Mutations of Btk cause X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency in mice. An Src homology domain 2-kinase linker region exists in all Src, Abl, ZAP70/Syk and Btk/Tec non-receptor tyrosine kinase families. Missense mutations in the Btk linker region can cause XLA, supporting ...

BOB.1/OBF.1 is a lymphocyte-restricted transcriptional coactivator. It binds together with the Oct1 and Oct2 transcription factors to DNA and enhances their transactivation potential. Mice deficient for the transcriptional coactivator BOB.1/OBF.1 show several defects in differentiation, function and signaling of B cells. In search of BOB.1/OBF.1 regulated genes we identified Btk--a cytoplasmic ...

Bruton's tyrosine kinase (Btk) is a non-receptor protein tyrosine kinase (PTK) that is expressed in all haemopoietic lineages except mature T cells and plasma cells. Despite the broad range of expression. mutations that inactivate this molecule affect primarily the development of the B-cell lineage. As a PTK, Btk could potentially be involved directly or indirectly in the processes that relate ...

The lack of BTK in X-linked agammaglobulinemia (XLA) patients does not affect monocytes and polymorphonuclear cells (PMN) phenotype and functions. In this study, we show that XLA patients had an increased frequency of the intermediate monocytes subset and that BTK-deficient monocytes and PMN had a normal expression of receptors involved in the activation and cellular responses. We demonstrate t...

A field population (SERD3) of Plutella xylostella L. collected in December 1994, and resistant to various insecticides, including Bacillus thuringiensis subsp. kurstaki (Btk) and B.t. subsp. aizawai (Bta), was selected with Btk (Btk-Sel) and Bta (Bta-Sel). Little evidence of cross-resistance was observed. Binding to midgut brush border membrane vesicles was examined for insecticidal crystal pro...

Loss of function of Bruton's tyrosine kinase (Btk) results in X-linked immunodeficiencies characterized by a broad spectrum of signaling defects, including those dependent on Src family kinase-linked cell surface receptors. A gain-of-function mutant, Btk*, induces the growth of fibroblasts in soft agar and relieves the interleukin-5 dependence of a pre-B-cell line. To genetically define Btk sig...

Bruton's tyrosine kinase (Btk) is essential for normal B lymphocyte development and function. The activity of Btk is partially regulated by transphosphorylation within its kinase domain by Src family kinases at residue Tyr-551 and subsequent autophosphorylation at Tyr-223. Activation correlates with Btk association with cellular membranes. Based on specific loss of function mutations, the Btk p...

The Tec family kinase Btk plays an important role in the regulation of phospholipase C gamma 2 (PLC gamma 2) downstream of the collagen receptor glycoprotein VI (GPVI) in human platelets. Platelets also express a second member of this family, Tec; however, its function has not been analyzed. To address the role of Tec, we analyzed Btk-/-, Tec-/-, and Btk/Tec double-deficient (Btk-/-/Tec-/-) pla...

The Tec family kinase Btk plays an important role in the regulation of phospholipase C 2 (PLC 2) downstream of the collagen receptor glycoprotein VI (GPVI) in human platelets. Platelets also express a second member of this family, Tec; however, its function has not been analyzed. To address the role of Tec, we analyzed Btk / , Tec / , and Btk/Tec double-deficient (Btk / /Tec / ) platelets. Tec ...

Btk plays crucial roles in the differentiation and activation of B and myeloid cells. Despite drastic reductions of other Ig isotypes, paradoxically high IgE responses have been known in btk mutant mice. Here we show that btk(-/-) dendritic cells exhibit a more mature phenotype and a stronger in vitro and in vivo T cell-stimulatory ability than wild-type cells. Increased IgE responses were indu...