Functionality of the Bruton’s tyrosine kinase from Mexican patients with XLA. (138.18)

Abstract X-linked agammaglobulinemia (XLA) is a primary immunodeficiency originated from mutations in the gene encoding Bruton’s tyrosine Kinase (Btk). Btk is a vital protein in the B cell signaling machinery. L111P and E605G are two recently characterized mutations in Mexican patients suffering XLA; they gave us the basis for a more detailed study of the effects of these mutations in the conformation and functionality of Btk. In silico assays showed that L111 and E605 residues are fundamental for the activations and functionality of the Btk. Btk from the two patients and a healthy control were expressed in the Btk-deficient DT40 cell line, in order to confirm the predictions obtained in silico. The absence of the Btk catalytic activity of the patients was reflected in the lack of the Y551 phosphorylation. This may resulted in a reduced activation of PLC-ã2 that was reflected by reduction of intracellular calcium flux. This work show that L111 and E605 residues are fundamental in the structural conformation of the Btk and that in silico analysis can be a useful tool for the analysis of Btk mutations found in primary immunodeficiency patients. Supported by CONACyT, project No. 70062