BCMA, a member of the TNF receptor superfamily, binds to BAFF and APRIL. BCMA is expressed on mature B-cells and other B-cell lines and plays an important role in B cell development, function and regulation. BCMA also has the capability to activate NF-kappaB and JNK. The human BCMA gene codes for a 184 amino acid type I transmembrane protein, which contains a 54 amino acid extracellular domain, a 23 amino acid transmembrane domain, and a 107 amino acid cytoplasmic domain. Recombinant soluble BCMA is a 50 amino acid polypeptide (5.3 kDa) comprising the TNFR homologous region of the BCMA protein.