4-1 BB Ligand, Recombinant, Human (4-1BBL, CD137L, TNFSF9, Tumor necrosis factor ligand superfamily member 9)

Human 4-1BB Ligand (4-1BBL, CD137L) is a 32kD type II transmembrane protein that belongs to TNF superfamily (TNFSF) of molecules.1-4 The human 4-1BBL cDNA encodes a 254 amino acid (aa) protein that contains a 25aa N-terminal cytoplasmic domain, a 23aa transmembrane segment, and a 206aa C-terminal extracellular region.5 The extracellular domain (ECD) of 4-1BBL has a jelly-roll, b-sandwich tertiary structure that is similar to other TNFSF members. There is only one cysteine in the human ECD, and no potential N-linked glycosylation sites. The potential exists, however, for O-linked glycosylation. The human 4-1BBL ECD shares 32% and 35% aa identity with mouse and rat ECD, respectively. In the cytoplasmic domain, human 4-1BBL is 55aa shorter than the equivalent region in rodents. 4-1BBL is expressed by activated B cells, macrophages, dendritic cells, activated Tcells, neurons and astrocytes.2, 3, 6 A 26kD soluble form of 4-1BBL is known to occur in human. Although it is presumably generated by MMP activity, its amino acid size is currently unreported.4 The soluble form is bioactive. Human 4-1BBL signals through both CD137/4-1BB and itself. Its cytoplasmic tail participates in reverse signaling that induces apoptosis in T cells and cytokine secretion (IL-6; TNF-a) by monocytes.7, 8 4-1BBL binding to CD137/4-1BB produces a number of effects. Its seems to play a key role in the T cell recall response. It maintains T cell numbers at the end of a primary response, and induces CD4+ and CD8+ T cells to proliferate and secrete cytokines such as IL-2 and IFN-g in CD4+ cells, and IFN-g in CD8+ cells.9, 10 Source: Recombinant, Human from E. coli Endotoxin: (same/less than) 0.1ng/ug (1EU/ug) Biological Activity: Determined by the dose-dependent stimulation of IL-8 production by human PBMC (peripheral blood mononuclear cells). The ED50 for this effect is 5-10ng/ml. Please Note: Results may vary with PBMC (peripheral blood mononuclear cells) donors. Reconstitution: We recommend a quick spin followed by reconstitution in water to a concentration of 0.1-1.0 mg/ml. This solution can then be diluted into other aqueous buffers and stored at 4 degrees C for 1 week or -20 degrees C for future use. Stability: The Lyophilized protein is stable for a few weeks at room temperature, but best stored at -20 degrees C. Reconstituted 4-1BBL should be storred in working aliquots at -20 degrees C. Country of Origin: USA