TACI (TNFRSF13B)

TACI, a member of the TNF Receptor superfamily, is expressed in the small intestine, spleen, thymus, peripheral blood leukocytes, activated T cells, and resting B cells. TACI binds to both APRIL and BAFF and can stimulate the activation of transcription factors; NF-kappaB, AP-1, and mediates calcineurin dependent activation of NF-AT (nuclear-factor of activated T cells) . TACI also plays a key role in the stimulation of B and T cell function. Soluble TACI inhibits APRIL-stimulated proliferation of primary B-cells by blocking the binding of APRIL to the membrane anchored TACI receptor. Recombinant human TACI is a soluble 160 amino acid polypeptide (17.8 kDa) comprising the TNFR homologous cysteine rich extracellular domain of the TACI protein.