The Protein Product of the ccb ! Protooncogene Is Phosphorylated after B Cell Receptor Stimulation and Binds the SH 3 Domain of Bruton ' s Tyrosine Kinase

X-linked agammaglobulinemia, a B cell immunodeficiency, is caused by mutations in the Bruton's tyrosine kinase (Btk) gene. The absence of a functional Btk protein leads to a failure of B cell differentiation and antibody production. B cell receptor stimulation leads to the phosphorylation of the Btk protein and it is, therefore, likely that Btk is involved… (More)