Mouse TNF RI/TNFRSF1A Alexa Fluor® 532-conjugated Antibody

TNF receptor 1 (TNF RI; also called TNF R‑p55/p60, TNFRSF1A and CD120a) is a type I transmembrane protein that belongs to the TNF receptor superfamily (1, 2). TNF RI is widely expressed and is present on the cell surface as a trimer of 55 kDa subunits. It serves as a receptor for both TNF‑ alpha and TNF‑ beta/lymphotoxin. Each subunit contains four TNF‑ alpha trimer‑binding cysteine‑rich domains (CRD) in its extracellular domain (ECD) (1‑6). TNF‑ alpha binding to TNF R1 induces the sequestration of TNFRI in lipid rafts, where it activates NF kappaB and is cleaved by ADAM‑17/TACE (7, 8). Release of the 28‑34 kDa TNF RI ECD occurs constitutively, and in response to products of pathogens such as LPS, CpG DNA or S. aureus protein A (1, 7‑12). Full‑length TNF RI may also be released in exosome‑like vesicles (12). Such release helps to resolve inflammatory reactions as it down‑regulates cell surface TNF RI and provides soluble TNF RI to bind TNF‑ alpha (6, 13, 14). Exclusion from lipid rafts causes endocytosis of TNF RI complexes and induces apoptosis (7, 15). Although there is a second receptor for TNF‑ alpha (TNF R2), TNF RI is thought to mediate most of the cellular effects of TNF‑ alpha (3). TNF R1 is essential for proper development of lymph node germinal centers and Peyer’s patches, and for combating intracellular pathogens such as Listeria monocytogenes (1‑3). Mouse TNF RI is a 454 amino acid (aa) protein that contains a 21 aa signal sequence and a 191 aa ECD with a PLAD domain (6). This mediates constitutive trimer formation. The PLAD domain is followed by four CRDs, a 23 aa transmembrane domain, and a 219 aa cytoplasmic sequence that contains a neutral sphingomyelinase activation domain and a death domain (16). The ECD of mouse TNF RI shows 67%, 70%, 64%, 70% and 88% aa identity with canine, feline, procine, human and rat TNF RI, respectively; and it shows 23% aa identity with the ECD of TNF RII.