Transmembrane activator and CAML interactor

"TACI" redirects here. The term may also refer to Total Anterior Circulation Infarct or Turks and Caicos Islands.

Transmembrane activator and CAML interactor (TACI), also known as tumor necrosis factor receptor superfamily member 13B (TNFRSF13B) is a protein that in humans is encoded by the TNFRSF13B gene.

TNFRSF13B
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1XU1, 1XUT
Identifiers
Aliases	TNFRSF13B, CD267, CVID, CVID2, RYZN, TACI, TNFRSF14B, IGAD2, tumor necrosis factor receptor superfamily member 13B, TNF receptor superfamily member 13B
External IDs	OMIM: 604907; MGI: 1889411; HomoloGene: 49320; GeneCards: TNFRSF13B; OMA:TNFRSF13B - orthologs
Gene location (Human) Chr. Chromosome 17 (human)[1] Band 17p11.2 Start 16,929,816 bp[1] End 16,972,118 bp[1]
Gene location (Mouse) Chr. Chromosome 11 (mouse)[2] Band 11|11 B2 Start 61,017,581 bp[2] End 61,040,198 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in spleen apex of heart lymph node tendon of biceps brachii muscle of thigh bone marrow cells gastrocnemius muscle cecum appendix parotid gland Top expressed in spleen mesenteric lymph nodes bone marrow blood thymus stroma of bone marrow granulocyte tibiofemoral joint subcutaneous adipose tissue embryo More reference expression data BioGPS More reference expression data
Gene ontology Molecular function protein binding signaling receptor activity Cellular component integral component of membrane integral component of plasma membrane membrane plasma membrane Biological process cell surface receptor signaling pathway tumor necrosis factor-mediated signaling pathway adaptive immune response immune system process B cell homeostasis hematopoietic progenitor cell differentiation negative regulation of B cell proliferation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 23495 57916 Ensembl ENSG00000240505 ENSMUSG00000010142 UniProt O14836 Q9ET35 RefSeq (mRNA) NM_012452 NM_021349 RefSeq (protein) NP_036584 NP_067324 Location (UCSC) Chr 17: 16.93 – 16.97 Mb Chr 11: 61.02 – 61.04 Mb PubMed search [3] [4]
Wikidata
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TNFRSF13B is a transmembrane protein of the TNF receptor superfamily found predominantly on the surface of B cells, which are an important part of the immune system.^[5] TACI recognizes three ligands: APRIL, BAFF and CAML.

Function

TACI is a lymphocyte-specific member of the tumor necrosis factor (TNF) receptor superfamily. It was originally discovered because of its ability to interact with calcium-modulator and cyclophilin ligand (CAML). TACI was later found to play a crucial role in humoral immunity by interacting with two members of the TNF family: B-cell activating factor (BAFF) and a proliferation-inducing ligand (APRIL).^[6] These proteins signal through TACI inducing activation of several transcription factors including NFAT, AP-1, and NF-kappa-B which then modulate cellular activities. Defects in the function of TACI can lead to immune system diseases and has shown to cause fatal autoimmunity in mice.^[7]

TACI controls T cell-independent B cell antibody responses, isotype switching, and B cell homeostasis.^{[citation needed]}

Clinical significance

TACI mutations are associated with immunodeficiency in humans, as a significant proportion of common variable immunodeficiency (CVID) patients have TACI mutations.^{[citation needed]} People with this condition produce abnormally low amounts of antibodies, which are needed for protection against infections.

In humans, the gene encoding this protein is located within the Smith–Magenis syndrome region on chromosome 17.^[5]

TACI is currently being targeted for autoimmunity and B cell malignancies via atacicept, a recombinant fusion protein that binds the TACI ligands BAFF and APRIL.^[8]

Interactions

TNFRSF13B has been shown to interact with B-cell activating factor,^[9][10] TRAF6,^[10] TRAF5,^[10] TNFSF13,^[6] TRAF2^[10] and CAMLG.^[10][11]