Btk Non-receptor tyrosine kinase indispensable for B lymphocyte development, differentiation and signaling. Binding of antigen to the B-cell antigen receptor (BCR) triggers signaling that ultimately leads to B-cell activation. After BCR engagement and activation at the plasma membrane, phosphorylates PLCG2 at several sites, igniting the downstream signaling pathway through calcium mobilization, followed by activation of the protein kinase C (PKC) family members. PLCG2 phosphorylation is performed in close cooperation with the adapter protein B-cell linker protein BLNK. BTK acts as a platform to bring together a diverse array of signaling proteins and is implicated in cytokine receptor signaling pathways. Plays an important role in the function of immune cells of innate as well as adaptive immunity, as a component of the Toll-like receptors (TLR) pathway. The TLR pathway acts as a primary surveillance system for the detection of pathogens and are crucial to the activation of host defense. Especially, is a critical molecule in regulating TLR9 activation in splenic B-cells. Within the TLR pathway, induces tyrosine phosphorylation of TIRAP which leads to TIRAP degradation. BTK plays also a critical role in transcription regulation. Induces the activity of NF-kappa-B, which is involved in regulating the expression of hundreds of genes. BTK is involved on the signaling pathway linking TLR8 and TLR9 to NF-kappa-B. Transiently phosphorylates transcription factor GTF2I on tyrosine residues in response to BCR. GTF2I then translocates to the nucleus to bind regulatory enhancer elements to modulate gene expression. ARID3A and NFAT are other transcriptional target of BTK. BTK is required for the formation of functional ARID3A DNA-binding complexes. There is however no evidence that BTK itself binds directly to DNA. BTK has a dual role in the regulation of apoptosis. Belongs to the protein kinase superfamily. Tyr protein kinase family. TEC subfamily. Predominantly expressed in B-lymphocytes. 2 human isoforms generated by alternative promoter usage have been reported. Note: This description may include information from UniProtKB.
Protein type: EC 2.7.10.2; Kinase, protein; Protein kinase, TK; Protein kinase, tyrosine (non-receptor); TK group; Tec family
Chromosomal Location of Human Ortholog: X E3|X 56.18 cM
Cellular Component:  cytoplasm; cytoplasmic vesicle; cytosol; membrane; membrane raft; nucleus; perinuclear region of cytoplasm; plasma membrane
Molecular Function:  ATP binding; identical protein binding; kinase activity; lipid binding; metal ion binding; non-membrane spanning protein tyrosine kinase activity; nucleotide binding; phosphatidylinositol-3,4,5-trisphosphate binding; protein binding; protein kinase activity; protein tyrosine kinase activity; transferase activity
Biological Process:  adaptive immune response; apoptotic process; B cell affinity maturation; B cell receptor signaling pathway; cell maturation; cellular response to interleukin-7; cellular response to molecule of fungal origin; cellular response to reactive oxygen species; histamine secretion by mast cell; I-kappaB kinase/NF-kappaB signaling; immune system process; innate immune response; intracellular signal transduction; negative regulation of B cell proliferation; negative regulation of cytokine production; peptidyl-tyrosine autophosphorylation; peptidyl-tyrosine phosphorylation; phosphorylation; positive regulation of type I hypersensitivity; positive regulation of type III hypersensitivity; protein autophosphorylation; protein phosphorylation; response to organic substance; T cell receptor signaling pathway
Reference #:  P35991 (UniProtKB)
Alt. Names/Synonyms: Agammaglobulinaemia tyrosine kinase; Agammaglobulinemia tyrosine kinase; AI528679; ATK; B-cell progenitor kinase; BPK; Bruton agammaglobulinemia tyrosine kinase; Bruton tyrosine kinase; Bruton's tyrosine kinase; Btk; Kinase EMB; OTTMUSP00000020834; Tyrosine-protein kinase BTK; Tyrosine-protein kinase BTK (Brutons tyrosine kinase) (Agammaglobulinaemia tyrosine kinase) (ATK) (B cell progenitor kinase) (BPK) (Kinase EMB); X-linked immune deficiency; xid
Gene Symbols: Btk
Molecular weight: 76,437 Da
Basal Isoelectric point: 8.05  Predict pI for various phosphorylation states
CST Pathways:  B Cell Receptor Signaling  |  Tyrosine Kinases & Substrates
Protein-Specific Antibodies, siRNAs or Recombinant Proteins from Cell Signaling Technology® Total Proteins
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Btk

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Cross-references to other databases:  AlphaFold  |  STRING  |  Reactome  |  BioGPS  |  KinBase  |  Pfam  |  RCSB PDB  |  ENZYME  |  Phospho.ELM  |  NetworKIN  |  UniProtKB  |  Entrez-Gene  |  Ensembl Gene