Tumor necrosis factor receptor superfamily member 1B is a 461 amino acids protein that belongs to the TNFR (tumor necrosis factor receptor) superfamily characterized by cysteine-rich extracellular domains. It contains 4 TNFR-Cys repeats. TNFRII is expressed in fetal brain. TNFRII is strongly expressed at the cartilage-pannus junction, and plays a major role in a subset of families with multiple cases of rheumatoid arthritis (RA). This receptor mediates most of the metabolic effects of TNF-alpha. Isoform 2 blocks TNF-alpha-induced apoptosis, which suggests that it regulates TNF-alpha function by antagonizing its biological activity.