Bruton's tyrosine kinase

Bruton's tyrosine kinase (abbreviated Btk or BTK) also known as tyrosine-protein kinase BTK is an is_associated_with::enzyme that in humans is encoded by the BTK is_associated_with::gene. BTK is a is_associated_with::kinase that plays a crucial role in is_associated_with::B-cell development.

Function
Its exact is_associated_with::mechanism of action remains unknown, but it plays a crucial role in is_associated_with::B cell maturation as well as is_associated_with::mast cell activation through the high-affinity is_associated_with::IgE receptor.

Btk contains a is_associated_with::PH domain that binds is_associated_with::phosphatidylinositol (3,4,5)-trisphosphate (PIP3). PIP3 binding induces Btk to phosphorylate is_associated_with::phospholipase C, which in turn hydrolyzes PIP2, a is_associated_with::phosphatidylinositol, into two second messengers, is_associated_with::inositol triphosphate (IP3) and diacylglycerol (DAG), which then go on to modulate the activity of downstream proteins during B-cell signalling.

Clinical significance
Mutations in the BTK gene are implicated in the is_associated_with::primary immunodeficiency disease is_associated_with::X-linked agammaglobulinemia (is_associated_with::Bruton's agammaglobulinemia). Patients with XLA have normal pre-B cell populations in their is_associated_with::bone marrow but these cells fail to mature and enter the circulation. The Btk gene is located on the is_associated_with::X chromosome. At least 400 is_associated_with::mutations of the BTK gene have been identified.

Discovery
Bruton's is_associated_with::tyrosine kinase was discovered in 1993 and is named for is_associated_with::Ogden Bruton, who first described XLA in 1952.

Interactions
Bruton's tyrosine kinase has been shown to interact with:


 * is_associated_with::ARID3A
 * BLNK,
 * CAV1,
 * is_associated_with::GNAQ,
 * is_associated_with::GTF2I,
 * is_associated_with::PLCG2,
 * PRKD1, and
 * is_associated_with::SH3BP5.