Transmembrane activator and CAML interactor

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

TNFRSF13B is a transmembrane protein of the is_associated_with::TNF receptor superfamily found predominantly on the surface of is_associated_with::B cells, which are an important part of the immune system. TACI recognizes three ligands: APRIL, is_associated_with::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: BAFF and APRIL. These proteins signal through TACI inducing activation of several transcription factors including is_associated_with::NFAT, AP-1, and is_associated_with::NF-kappa-B which then modulate cellular activities. Defects in the function of TACI can lead to immune system diseases.

TACI controls T cell-independent B cell antibody responses, is_associated_with::isotype switching, and B cell is_associated_with::homeostasis.

Clinical significance
TACI mutations are associated with immunodeficiency in humans, as a significant proportion of is_associated_with::CVID patients have TACI mutations. People with this condition produce abnormally low amounts of is_associated_with::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.

Interactions
TNFRSF13B has been shown to interact with is_associated_with::B-cell activating factor, is_associated_with::TRAF6, is_associated_with::TRAF5, is_associated_with::TNFSF13, is_associated_with::TRAF2 and is_associated_with::CAMLG.