BAFFR is an atypical representative of the TNF-receptor super-family. BAFFR [BAFFR = B cell activating f actor of the TNF-f amily receptor; a.k.a. BR3, Bcmd] expression starts when the immature B cells develop to transitional B cells, which then receive BAFFR-dependent pro-survival signals to rescue them from premature cell death. At protein level, the BAFFR is expressed on the surface of all human peripheral B cell subsets except for plasma cells and for centroblasts located in the dark zone of germinal centers. Its expression is upregulated after the expression of functional B cell antigen receptors (BCR) in response to tonic BCR signaling, which enhances BAFFR expression by immature and transitional B cells

> 95% as determined by Bis-Tris PAGE