RANKL, aa85-245, Recombinant, Human (Receptor Activator of Nuclear Factor kappa B Ligand, Receptor A

RANK L, is a 39-45kD type II transmembrane (TM) protein in the tumor necrosis factor family, designated TNFSF11 (1-5). RANK L, produced by osteoblasts and bone marrow stromal cells, is required for differentiation of osteoclasts and stimulates bone resorption (4, 6). It is also produced by activated T cells and augments dendritic cell stimulation, RANK L-/- mice lack lymph nodes and have impaired thymocyte development (1-3, 6). The human RANK L cDNA encodes 317aa, including a 47aa cytoplasmic domain, a 21aa TM region, and a 249aa extracellular domain (ECD) with two potential N-linked glycosylation sites (note: aa85-245 of Accession # AAC51762 is identical to aa157-317 of SwissProt # O14788. This aa range contains the ECD trimerization and receptor-binding motifs, but not ECD proteolytic cleavage sites). Within the ECD, human RANK L shares 89%, 89%, 93% and 95% aa identity with mouse, rat, bovine and porcine RANK L, respectively. Mouse RANK L can stimulate human osteoclast differentiation (4). Like most TNF family members, RANK L can form trimers (1). Soluble 31, 25 and 24kD forms of RANK L can be created by usage of alternate start sites at aa74 or 146, or proteolytic cleavage by osteoblast- or stromal cell-derived ADAM10 (after aa139) or MMP14 (146aa), or bone metastatic prostate tumor-derived MT1-MMP (aa146) (5, 7, 8). Both TM and soluble extracellular RANK L act by engaging RANK receptors and are antagonized by the decoy receptor, OPG (osteoprotegrin) (2, 5). In resting cells, the majority of RANK L is stored in secretory lysosomes (9). In mammary epithelia, RANK L is upregulated by pregnancy hormones and is essential for the formation of a lactating mammary gland (10). In the brain, astrocyte RANK L mediates body temperature regulation (11). Pathologically, RANK L is thought to mediate post-menopausal osteoporosis, vascular calcification, progestin-induced breast cancer, cancer-induced bone disease, and osteopetrosis (in RANK L deficiencies) (12-16). Source: Recombinant corresponding to aa85-245 from human RANK L with an N-terminal Met expressed in E. coli. Molecular Weight: ~18.3kD, Endotoxin Level: <1EU/1ug (LAL), Biological Activity: Measured by its ability to induce osteoclast differentiation on RAW 264.7 mouse macrophages., The ED50 for this effect is typically 2-12ng/mL, Storage and Stability: Lyophilized powder may be stored at -20°C. Stable for 12 months at -20°C. Reconstitute with PBS. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Reconstituted product is stable for 6 months at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.