Zinc finger, Btk motif
IPR001562
Definition
The Btk-type zinc finger or Btk motif (BM) is a conserved zinc-binding motif containing conserved cysteines and a histidine that is present in certain eukaryotic signalling proteins. The motif is named after Bruton's tyrosine kinase (Btk), an enzyme which is essential for B cell maturation in humans and mice [[cite:PMID:8070576], [cite:PMID:15661031]]. Btk is a member of the Tec family of protein tyrosine kinases (PTK). These kinases contain a conserved Tec homology (TH) domain between the N-terminal pleckstrin homology (PH) domain ([interpro:IPR001849]) and the Src homology 3 (SH3) domain ([interpro:IPR001452]). The N-terminal of the TH domain is highly conserved and known as the Btf motif, while the C-terminal region of the TH domain contains a proline-rich region (PRR). The Btk motif contains a conserved His and three Cys residues that form a zinc finger (although these differ from known zinc finger topologies), while PRRs are commonly involved in protein-protein interactions, including interactions with G proteins [[cite:PMID:9280283], [cite:PMID:9796816]]. The TH domain may be of functional importance in various signalling pathways in different species PMID:8070576. A complete TH domain, containing both the Btk and PRR regions, has not been found outside the Tec family; however, the Btk motif on its own does occur in other proteins, usually C-terminal to a PH domain (note that although a Btk motif always occurs C-terminal to a PH domain, not all PH domains are followed by a Btk motif). 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, and that the Btk motif is packed against the PH domain PMID:8070576. The zinc-binding residues are a histidine and three cysteines, which are fully conserved in the Btk motif PMID:9218782.
9 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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