Bruton’s tyrosine kinase (BTK), also known as BPK or ATK, is a member of the TEC family of non-receptor protein tyrosine kinases, which also includes Bmx, Itk, and Tec. BTK is essential for B cell activation, signaling, and development. In addition to its role in B cell receptor pathways, BTK can interact with Fas, a TNFR family member involved in apoptosis, in a ligand-independent manner. Mutations in the BTK gene cause severe defects in B cell maturation, resulting in X-linked agammaglobulinemia (XLA).
