Mutation pattern was characterized in the Bruton's tyrosine kinase gene (BTK) in 26 patients with X-linked agammaglobulinemia, the first described immunoglobulin deficiency, and was related to BTK expression. A total of 24 different mutations were identified. Most BTK mutations were found to result
Bruton's tyrosine kinase associates with the actin-based cytoskeleton in activated platelets
β Scribed by Saikat Mukhopadhyay; Amanchy S.S. Ramars; Debabrata Dash
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 147 KB
- Volume
- 81
- Category
- Article
- ISSN
- 0730-2312
- DOI
- 10.1002/jcb.1088
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β¦ Synopsis
Abstract
Bruton's tyrosine kinase (Btk) plays a crucial role in the maturation and differentiation of Bβlymphocytes and immunoglobulin synthesis. Recently Btk has been described to be present in significant amount in human platelets. To investigate the regulation of this kinase in the platelets we studied its subcellular redistribution in the resting and activated cells. In the resting platelets Btk was almost absent from the actinβbased cytoskeleton. Upon challenge of the platelet thrombin receptor upto 30% of total Btk appeared in the cytoskeleton and the protein underwent phosphorylation on tyrosine. Translocation of Btk to the cytoskeleton but not aggregation was prevented by cytochalasin B, which inhibits actin polymerization. Wortmannin and genistein (inhibitors of phosphoinositide 3βkinase and protein tyrosine kinase, respectively) decreased while phenylarsine oxide (a tyrosine phosphatase inhibitor) increased the cytoskeletal content of Btk. The association of Btk with the cytoskeleton was regulated by integrin Ξ±~IIb~Ξ²~3~ and partly reversible. Taken together, these data suggest that Btk might be a component of a signaling complex containing specific cytoskeletal proteins in the activated platelets. J. Cell. Biochem. 81: 659β665, 2001. Β© 2001 WileyβLiss, Inc.
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