Recombinant protein corresponding to Arg71-Glu254 from human 4-1BB, expressed in E. coli.
4-1BB ligand (4-1BBL, also 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 254aa 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, beta-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 T cells, 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 cytokkine secretion (IL-6, TNF-alpha) by monocytes. 7, 8 4-1BBL binding to CD137/4-1BB produces a number of effects. It 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-gamma in CD4 + cells, and IFN-gamma in CD84-1BB Ligand/TNFSF9. Applications: Suitable for use in Flow Cytometry. Other applications not tested. Optimal dilutions to be determined by the researcher. Recommended Dilution: Flow Cytometry: Designed to quantitatively determine the percentage of cells bearing 4-1BB Ligand/TNFSF9 within a population and qualitatively determine the density of 4-1BB Ligand/TNFSF9 on cell surfaces by flow cytometry. Washed cells are incubated with the phycoerythrin-labeled monoclonal antibody, which binds to cells expressing 4-1BB Ligand/TNFSF9. Unbound phycoerythrin-conjugated antibody is then washed from the cells. Cells expressing 4-1BB Ligand/TNFSF9 are fluorescently stained, with the intensity of staining directly proportional to the density of expression of 4-1BB Ligand/TNFSF9. Cell surface expression of 4-1BB Ligand/TNFSF9 is determined by flow cytometric analysis using 488nm wavelength laser excitation and monitoring emitted fluorescence with a detector optimized to collect peak emissions at 565-605nm. Storage and Stability: Store product at 4C in the dark. DO NOT FREEZE! Stable at 4C for 12 months after receipt as an undiluted liquid. Dilute required amount only prior to immediate use. Further dilutions can be made in assay buffer. Caution: PE conjugates are sensitive to light. For maximum recovery of product, centrifuge the original vial prior to removing the cap.
