Recombinant Human Osteoprotegerin/TNFRSF11B Protein

Recombinant Human Osteoprotegerin/TNFRSF11B Protein Summary

Product Specifications

Product Datasheets

Carrier Free

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.

Background: Osteoprotegerin/TNFRSF11B

Osteoprotegerin (OPG), also called OCIF (osteoclastogenesis inhibitory factor) is a secreted 55-60 kDa protein that regulates bone density (1-3). As a member of the tumor necrosis factor receptor (TNFR) superfamily of proteins, it is designated TNFRSF11B (1-4). Human OPG cDNA encodes 401 amino acids (aa) including a 21 aa signal peptide and a 380 aa mature soluble protein with four TNFR domains, two death domains and a heparin-binding region (4). The cysteine-rich TNFR domains are essential for ligand interaction, while a cysteine at the C-terminus mediates homodimerization (4). Mature human OPG shares 86%, 87%, 92%, 92% and 88% amino acid sequence identity with mouse, rat, equine, canine and bovine OPG, respectively. OPG is widely expressed and constitutively released as a homodimer by mesenchymal stem cells, fibroblasts and endothelial cells (1, 2, 5, 7). Regulation of its expression by estrogen, parathyroid hormone and cytokines is complex and changes with age (2). OPG has been called a decoy receptor for the TNF superfamily ligands, TRANCE (tumor necrosis factor-related activation-induced cytokine), also called RANK L (receptor activator of NF kappa B ligand), and TRAIL (TNF-related apoptosis-inducing ligand), which also bind TNF family receptors RANK and TRAIL receptors 1-4, respectively (2, 6). TRAIL decreases the release of OPG from cells that express it, while OPG inhibits TRAIL-induced apoptosis (5, 6). Expression of RANK L on the cell surface, and thus its ability to stimulate osteoclastogenesis, is regulated by OPG by intracellular and extracellular mechanisms (7). Within osteoblasts, interaction of the basic domain of OPG with RANK L in the Golgi inhibits RANK L secretion (7). Extracellularly, OPG binding to RANK L results in
clathrin-mediated internalization and degradation of both proteins (7, 8). Binding of OPG by syndecan-1 heparin sulfates on multiple myeloma cells also results in OPG internalization and degradation, contributing to bone loss (8, 9). OPG deficiency can cause juvenile Paget’s disease in humans, and insufficient OPG to balance with RANK L and RANK can produce osteoporosis and vascular calcification in both mice and humans (2, 10, 11).

Related Research Areas

• Cytokine and Growth Factor Receptors on VSMC
• Gametes and Fertilization
• Glucose Homeostasis
• Molecules Secreted by VSMC
• Regulation of Apoptosis by TNF Superfamily Members
• TNF Superfamily
• TNF Superfamily Receptors