OPN

Osteopontin (OPN) is a highly phosphorylated glycoprotein consisting of approximately 314 aa. It was first identified in 1985 by Franzen and Heinegård as sialoprotein isolated from bovine bone matrix.

A unit of mass of nascent OPN is 33kDa in humans and 32kDa in mice.It is expressed as a sequence of about 300 aa (305 in zebrafish, 264 in chickens, 294 in mice, 314 in humans). However, the apparent molecular weight of OPN according to SDS-PAGE can range from 45 to 75kDa because of posttranslational modifications such as O-linked glycosylation, tyrosine sulfation and sialylation, and multiple Ser/Thr phosphorylations. Those modifications vary according to the cellular origin of OPN and greatly affect the function of the protein.4 Basal pI 4.37. Soluble in water. Stable in 1xPBS at 4°C within 2–4weeks.

Increased OPN secretion has been correlated with cell proliferation in various malignancies, including breast and prostate cancer, squamous cell carcinoma, melanoma, osteosarcoma, and glioblastoma.

OPN is constitutively expressed in many cells but is upregulated under various conditions, particularly in inflammation and cancer progression. The following variants of growth factors and cytokines (including LPS, NO, Ang II, IL-1b, IL-2, IL-3, IFN-γ, TNF-α, TGF-β) have been reported to upregulate OPN expression.

OPN produced by tumor cells is structurally different compared to that produced by normal cells. Therefore, it has been reported that blocking the production of OPN by using antibodies or synthetic peptides that recognize specific epitopes of tumor-derived OPN may block cell proliferation.

For research use only. Not for use in diagnostic procedures.
Please refer to the attached General ELISA KIT Procedure (sandwich, competitive & Indirect ELISA)

The Human OPN ELISA (Enzyme-Linked Immunosorbent Assay) kit is an in vitro enzyme-linked immunosorbent assay for the quantitative measurement of human OPN in serum, plasma, cell culture supernatants and urine.

Osteopontin (OPN) is a secreted glycoprotein and is assumed to be associated with various cellular processes such as adhesion, migration, and biomineralization in diverse tissues. Osteopontin acts as a ligand to αvβ3 integrin and possibly other receptors. In addition to its involvement in mineralized matrix formation, osteopontin can also function as a cytokine that stimulates the release of IFNγ (interferon γ) and IL-12 (interleukin 12), while inhibiting the production of IL-10. Osteopontin is involved in inflammation and also regulates immunity against infectious diseases. It also co-stimulates T cell proliferation. Osteopontin has proinflammatory functions and is associated with multiple sclerosis. It participates in inflammation in Crohn′s Disease. Osteopontin plays a crucial role in bone remodelling and retards ectopic calcification by inhibiting the formation of hydroxyapatite. OPN is thought to prevent renal stone formation by suppressing nucleation, growth and aggregation of calcium oxalate crystals.