BAFF/TNFSF13B/CD257 Trimer His Tag Protein, Human

BAFF (B cell activating factor), also known as BLyS/TALL-1/TNFSF13B, is a member of the TNF superfamily that exists as a homotrimer and regulates B cell survival through specific binding to three receptors: BAFF-R, TACI, and BCMA. BAFF is a type II transmembrane protein with an extracellular domain forming a β-sheet-rich "sandwich" structure; the receptor-binding interface comprises the DE loop and N-terminal loop, whose surface charge distribution determines high-affinity binding to BAFF-R and cross-recognition with TACI/BCMA. BAFF serves as a central regulator of B cell development, homeostasis maintenance, and humoral immunity, promoting transitional B cell survival, germinal center reactions, and antibody class switching. BAFF overexpression is closely associated with autoimmune diseases including systemic lupus erythematosus, rheumatoid arthritis, and Sjögren's syndrome, with serum levels serving as disease activity biomarkers; the BAFF-targeting monoclonal antibody Belimumab represents the first new drug approved for SLE in 50 years, significantly improving patient outcomes by blocking BAFF-receptor interactions and reducing autoreactive B cells, marking a landmark milestone in B cell-targeted therapy.