X-linked agammaglobulinemia

Gene Information


HUGO name: BTK


  • AGMX1
  • AT
  • ATK
  • BPK
  • B cell progenitor kinase
  • IMD1
  • PSCTK1
  • XLA
  • Bruton agammaglobulinemia tyrosine kinase
  • Tyrosine-protein kinase BTK


Reference sequences

Chromosomal location



Protein Information


Protein function:

Plays a crucial role in B-cell ontogeny. Transiently phosphorylates GTF2I on tyrosine residues in response to B cell receptor crosslinking.

Catalytic activity:

ATP + a protein tyrosine = ADP + protein tyrosine phosphate.


Binds GTF2I through the PH domain.

Subcellular location:

Cytoplasmic and membrane-associated.

Post-translational modification:

Autophosphorylated on Tyr-223 and Tyr-551. The tyrosine phosphorylation of Tyr-223 may create a docking site for a SH2 containing protein.

Structures (PDB)

1BTK PH domain and BTK motif from Bruton's tyrosine kinase mutant R28C
1AWW SH3 domain from Bruton's tyrosine tinase, NMR, 42 structures
1AWX SH3 domain from Bruton's tyrosine kinase, NMR, minimized average structure
1B55 PH domain from Bruton's tyrosine kinase in complex with inositol 1,3,4,5-tetrakisphosphate
1BWN PH domain and BTK motif from Bruton's tyrosine kinase mutant E41K in complex with Ins(1,3,4,5)P4
1K2P Crystal Structure Of Bruton'S Tyrosine Kinase Domain


Expression pattern for human

Tissue Expression (%) Clones
Pheochromocytoma 22.49 1:1560
Leukocyte 15.62 4:8982
Lymph 9.26 17:64395
B-cells 8.49 4:16533
Tonsil, enriched for germinal center B-cells 6.72 7:36522
Lung metatastic chondrosarcoma 5.44 1:6448
Corresponding non cancerous liver tissue 5.04 2:13909
Mixed 4.65 8:60341
Bone marrow 3.53 2:19854
Human skeletal muscle 3.26 1:10746

Animal models