PROSITE documentation PDOC51113
Zinc finger Btk-type profile


The Btk-type zinc finger or Btk motif (BM) is a domain of ~37 amino acids present in eukaryotic signalling proteins. The domain is named after Bruton's tyrosine kinase (Btk), an enzyme which is essential for B cell maturation in humans and mice [1,2]. Btk and other protein tyrosine kinases (PTK) of the Tec family contain a conserved Tec homology (TH) region between the N-terminal pleckstrin homology (PH) domain (see <PDOC50003>) and the Src homology 3 (SH3) domain (see <PDOC50002>). The Btk domain forms the N-terminal part of the Tec homology region while the C-terminal portion of TH contains a proline-rich region. The Btk domain occurs in some proteins outside the Tec family of PTKs, where it is also C-terminal to a PH domain. The Btk-type zinc finger seems to be involved in protein-protein interactions, and it can interact with G proteins [3,4].

The crystal structures of Btk show that the Btk-type zinc finger has a globular core, formed by a long loop which is held together by a zinc ion (see <PDB:1BTK>). The zinc-binding residues are a histidine and three cysteines, which are fully conserved in the Btk motif [1,2,3,4,5].

Some proteins known to contain a Btk-type zinc finger:

  • Mammalian Bruton's tyrosine kinase (Btk), a protein tyrosine kinase involved in modulation of diverse cellular processes. Mutations affecting Btk are the cause of X-linked aγglobulinemia (XLA) in humans and X-linked immunodeficiency in mice.
  • Mammalian Tec, Bmx, and Itk proteins, which are tyrosine protein kinases of the Tec subfamily.
  • Drosophila tyrosine-protein kinase Btk29A, which is required for the development of proper ring canals and of male genitalia and required for adult survival.
  • Mammalian Ras GTPase-activating proteins (RasGAP), which regulate the activation of inactive GDP-bound Ras by converting GDP to GTP.

The profile we developed covers the entire Btk-type zinc finger.

Last update:

April 2005 / First entry.


Technical section

PROSITE method (with tools and information) covered by this documentation:

ZF_BTK, PS51113; Zinc finger Btk-type profile  (MATRIX)


1AuthorsVihinen M. Nilsson L. Smith C.I.E.
TitleTec homology (TH) adjacent to the PH domain.
SourceFEBS Lett. 350:263-265(1994).
PubMed ID8070576

2AuthorsLindvall J.M. Blomberg K.E.M. Valiaho J. Vargas L. Heinonen J.E. Berglof A. Mohamed A.J. Nore B.F. Vihinen M. Smith C.I.E.
TitleBruton's tyrosine kinase: cell biology, sequence conservation, mutation spectrum, siRNA modifications, and expression profiling.
SourceImmunol. Rev. 203:200-215(2005).
PubMed ID15661031

3AuthorsVihinen M. Nore B.F. Mattsson P.T. Backesjo C.M. Nars M. Koutaniemi S. Watanabe C. Lester T. Jones A. Ochs H.D. Smith C.I.E.
TitleMissense mutations affecting a conserved cysteine pair in the TH domain of Btk.
SourceFEBS Lett. 413:205-210(1997).
PubMed ID9280283

4AuthorsJiang Y. Ma W. Wan Y. Kozasa T. Hattori S. Huang X.Y.
TitleThe G protein G alpha12 stimulates Bruton's tyrosine kinase and a rasGAP through a conserved PH/BM domain.
SourceNature 395:808-813(1998).
PubMed ID9796816

5AuthorsHyvonen M. Saraste M.
TitleStructure of the PH domain and Btk motif from Bruton's tyrosine kinase: molecular explanations for X-linked agammaglobulinaemia.
SourceEMBO J. 16:3396-3404(1997).
PubMed ID9218782

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