PROSITE documentation PDOC51113Zinc 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.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | Vihinen M. Nilsson L. Smith C.I.E. |
| Title | Tec homology (TH) adjacent to the PH domain. | |
| Source | FEBS Lett. 350:263-265(1994). | |
| PubMed ID | 8070576 |
| 2 | Authors | Lindvall 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. |
| Title | Bruton's tyrosine kinase: cell biology, sequence conservation, mutation spectrum, siRNA modifications, and expression profiling. | |
| Source | Immunol. Rev. 203:200-215(2005). | |
| PubMed ID | 15661031 | |
| DOI | 10.1111/j.0105-2896.2005.00225.x |
| 3 | Authors | Vihinen 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. |
| Title | Missense mutations affecting a conserved cysteine pair in the TH domain of Btk. | |
| Source | FEBS Lett. 413:205-210(1997). | |
| PubMed ID | 9280283 |
| 4 | Authors | Jiang Y. Ma W. Wan Y. Kozasa T. Hattori S. Huang X.Y. |
| Title | The G protein G alpha12 stimulates Bruton's tyrosine kinase and a rasGAP through a conserved PH/BM domain. | |
| Source | Nature 395:808-813(1998). | |
| PubMed ID | 9796816 | |
| DOI | 10.1038/27454 |
| 5 | Authors | Hyvonen M. Saraste M. |
| Title | Structure of the PH domain and Btk motif from Bruton's tyrosine kinase: molecular explanations for X-linked agammaglobulinaemia. | |
| Source | EMBO J. 16:3396-3404(1997). | |
| PubMed ID | 9218782 | |
| DOI | 10.1093/emboj/16.12.3396 |
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