Recombinant Human Osteopontin/OPN-a His-tag Protein, CF

Recombinant Human Osteopontin/OPN-a His-tag Protein, CF 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: Osteopontin/OPN

Osteopontin (OPN), previously called SPP1 (secreted phosphoprotein 1), Eta-1 (early T lymphocyte activation 1) or BSP (bone sialoprotein), is a secreted molecule in the SIBLING (small integrin-binding ligand N-linked glycoprotein) family of non-collagenous matricellular proteins (1-3). Human OPN is synthesized as a 317 amino acid (aa) precursor protein with a 16 aa signal peptide and a 301 aa mature protein (3). At the transcript level, at least five isoforms are generated: OPNa (full‐length), OPNb (lacking exon 5), OPNc (lacking exon 4), OPN4 (lacking exons 4 and 5), and OPN5 (alternative N‐terminus upstream of exon 4). Besides these variants, four additional isoforms have been described for OPN5 (OPN5b, OPN5c, OPN5d, and OPN5e) (4). Mature human OPN shares 64% and 62% aa sequence identity with mouse and rat OPN, respectively. OPN is highly acidic and has 26 potential Ser/Thr phosphorylation sites and a C-terminal CD44 binding site (1-5). Depending on tissue-specific modification by O- and N-glycosylation, sulfation, phosphorylation and transglutamination, OPN can be detected at 45-75 kDa (6, 7). The central region of OPN contains RGD and non-RGD binding sites for multiple integrins (3, 5). OPN receptors include alpha v ( beta 1, beta 3, or beta 5) and ( alpha 4, alpha 5, alpha 8, or alpha 9) beta 1‐integrins, receptor CD44, and epidermal growth factor receptor (12). Adjacent to the RGD motif is the sequence SVVYGLR (SLAYGLR in mouse) which serves as a cryptic binding site for additional integrins: it is masked in full length OPN but is exposed following OPN cleavage by thrombin in tumors and sites of tissue injury (8-10). OPN can also be cleaved by MMP-3, -7, -9, and -12 within the SVVYGLR motif and at sites closer to the C-terminus (9, 10). OPN is widely expressed and is prominent in mineralized tissues. It inhibits bone mineralization and kidney stone formation and promotes inflammation, cell adhesion and migration (1, 2, 5, 7). Its expression is upregulated during inflammation, obesity, atherosclerosis, cancer, and tissue damage, and contributes to the pathophysiology of these conditions (1, 2, 7, 10, 11). Osteopontin occurs in many healthy tissues and secretions as well, but the highest concentrations are found in milk. Its concentration in bovine milk is 0.018–0.022 g/L and ~0.138 g/L in human milk (13).

Related Research Areas

• Adhesion Molecules in Angiogenesis
• Adhesion Molecules on VSMC
• Adipose-derived Stem Cell Markers
• Cancer Biomarkers
• Extracellular Matrix Molecules
• Gametes and Fertilization
• HIF Transcription Factors
• Integrins and Associated Molecules
• Molecules Secreted by VSMC
• Osteoblast Markers
• Osteogenesis Markers
• Renal Markers