Osteopontin (OPN) is a calcium-binding glycosylated phosphoprotein secreted by many cell types, including osteoblasts, kidney tubule cells, macrophages, activated T cells, and vascular smooth muscle cells. Osteopontin is post-translationally modified; the molecular weight varies within the range of 44–66 kDa, depending on the level of glycosylation and phosphorylation. Thrombin cleaves osteopontin into N-terminal and C-terminal fragments. A variety of OPN isoforms exist within the cell, produced by differential splicing, post-translational modification, and proteolytic cleavage.
OPN contains an Arg-Gly-Asp (RGD) amino acid motif that is also found in other extracellular proteins that bind members of the integrin family of cell-surface receptors. This binding activity has been localized to the N-terminal fragment of osteopontin, generated by thrombin cleavage.
Osteopontin is also known as Spp-1, Apl-1, BNSP, bone sialoprotein 1, ETA-1, and minopontin.
ELISAs for Osteopontin Detection
These kits are solid-phase sandwich ELISAs using two antibodies that are highly specific to human, mouse, or rat OPN or its N-terminal fragments; one is precoated on the ELISA plate and the other is HRP-conjugated. These assay kits can be used to measure soluble human, mouse, or rat OPN protein in serum, EDTA plasma, synovial fluid, urine, or cell culture supernatants.
Antibodies for Osteopontin Detection
These products are affinity-purified IgG antibodies that recognize human, mouse, or rat OPN, or N-terminal fragments of OPN and OPN (O-17). The antibodies were raised in mouse or rabbit using a synthetic peptide and can be used for Western blot (WB) detection or immunohistochemical (IHC) detection of human OPN.
