Use at an assay-dependent concentration. For Sandwich ELISA pairing: Human Osteoprotegerin Antibody(Capture) (EPA1894C), with Human Osteoprotegerin Protein (EPA1894S) as assay standards. The reference range value is 62.5-8,000 pg/mL.
Target info
Function
Osteoprotegerin (OPG; official symbol TNFRSF11B, also called OCIF or TR1) is a secreted decoy receptor of the TNF receptor superfamily, encoded in humans by the TNFRSF11B gene on chromosome 8q24. It is produced by osteoblasts, osteocytes, vascular smooth muscle cells, endothelial cells, B lymphocytes, and many other cell types, and is released into the extracellular space and circulation as a soluble disulfide-linked homodimer. OPG lacks a transmembrane and cytoplasmic domain and therefore does not transduce signals itself; instead it binds with high affinity both membrane-bound and soluble RANKL (receptor activator of NF-kB ligand, TNFSF11), preventing RANKL from engaging its signaling receptor RANK on osteoclast precursors. By neutralizing RANKL, OPG blocks RANK-mediated NF-kB, NFATc1, and MAPK signaling that otherwise drives osteoclast differentiation, fusion, activation, and survival, thereby inhibiting osteoclastic bone resorption and promoting osteoclast apoptosis. The local RANKL/OPG ratio is the principal determinant of bone-remodeling balance: excess RANKL favors bone loss (osteoporosis, rheumatoid arthritis, tumor osteolysis), whereas excess OPG favors osteopetrosis. OPG also acts as a decoy receptor for the TNF-related apoptosis-inducing ligand TRAIL (TNFSF10), limiting TRAIL-induced apoptosis in some cell types, and has been implicated in protecting against vascular calcification and in immune tolerance. Loss-of-function TNFRSF11B mutations cause juvenile Paget's disease (early-onset osteolytic bone disease). Subcellularly, OPG is a secreted soluble circulating protein (a natural decoy receptor), not a membrane receptor.
