|Detection of Human Periostin/OSF-2 by Western Blot. Western blot shows lysates of human breast cancer tissue. PVDF membrane was probed with 1 µg/mL of Goat Anti-Human Periostin/OSF-2 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF3548) followed by HRP-conjugated Anti-Goat IgG Secondary Antibody (Catalog # HAF019). A specific band was detected for Periostin/OSF-2 at approximately 90-95 kDa (as indicated). This experiment was conducted using Immunoblot Buffer Group 8.|
|Periostin/OSF‑2 in Human Breast. Periostin/OSF‑2 was detected in immersion fixed paraffin-embedded sections of human breast using Goat Anti-Human Periostin/OSF‑2 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF3548) at 10 µg/mL overnight at 4 °C. Tissue was stained using the Anti-Goat HRP-DAB Cell & Tissue Staining Kit (brown; Catalog # CTS008) and counterstained with hematoxylin (blue). Specific staining was localized to stromal cells. View our protocol for Chromogenic IHC Staining of Paraffin-embedded Tissue Sections.|
|Immunoprecipitation of Human Periostin/OSF-2. Human Periostin/OSF-2 was immunoprecipitated from human milk samples diluted in 1X Sample Diluent Concentrate 2 (Catalog # DYC002) and incubated with 3 µg Goat Anti-Human Periostin/OSF‑2 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF3548) or Normal Goat IgG Control (Catalog # AB-108-C) plus 30 µL Protein G beads overnight. Immunoprecipitated Periostin/OSF-2 was detected by Western blot under reducing conditions using 1 µg/mL Goat Anti-Human Periostin/OSF‑2 Antigen Affinity-purified Polyclonal Antibody (Catalog # AF3548). View our recommended buffer recipes for immunoprecipitation.|
Human OSF-2 (Osteoblast-Specific Factor 2), also known as Periostin, is a 170 kDa secreted homodimeric protein that belongs to the periostin family of the FAS1 superfamily of molecules. It is a TGF-beta inducible molecule that serves as both an adhesion molecule and tumor suppressor. It is synthesized as an 836 amino acid (aa) precursor that contains a 21 aa signal sequence and an 815 aa mature region. It is unknown if the molecule has any significant glycosylation. The human homodimer is not disulfide-linked. The molecule consists of two distinct regions. The N-terminus contains an 55 aa EMI domain, while the C-terminus contains four 130 aa Fasciculin type 1 (FAS1) domains. The EMI domain is cysteine-rich and shows a highly basic alpha -helix. Each FAS1 repeat exhibits a novel seven-stranded beta -wedge with a multiple alpha -helical fold. Three alternate splice forms are known that are C-terminal to the fourfold FAS1 repeats. These mature molecules are 758 and 761 aa in length. The first shows a one aa substitution for aa 649-706 of the mature molecule. The second shows a one aa substitution for aa 649-676, and a deletion of 27 aa between aa 784-810 of the mature molecule. The significance of the alternate splice forms is not clear. OSF-2 is known to bind to alpha v beta 3 and alpha v beta 5 integrins. It is synthesized by smooth muscle cells, fibroblasts, osteoblasts, and multiple carcinoma cell types. OSF-2 induces expression of VEGFR2/KDR on endothelial cells (EC) by binding to EC alpha v beta 3. It also promotes cell transformation to a tumorigenic phenotype, accompanied by MMP-9 and fibronectin production and cell migration. Mature human OSF-2 is 91%, 96% and 91% aa identical to rat, dog, and mouse OSF-2, respectively.
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