|Detection of Mouse Serpin A8/Angiotensinogen by Western Blot. Western blot shows lysates of mouse liver tissue. PVDF membrane was probed with 1 µg/mL of Sheep Anti-Mouse Serpin A8/Angiotensinogen Antigen Affinity-purified Polyclonal Antibody (Catalog # AF6966) followed by HRP-conjugated Anti-Sheep IgG Secondary Antibody (Catalog # HAF016). A specific band was detected for Serpin A8/Angiotensinogen at approximately 55 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 8.|
|Serpin A8/Angiotensinogen in Mouse Intestine. Serpin A8/Angiotensinogen was detected in perfusion fixed frozen sections of mouse intestine using Sheep Anti-Mouse Serpin A8/Angiotensinogen Antigen Affinity-purified Polyclonal Antibody (Catalog # AF6966) at 1.7 µg/mL overnight at 4 °C. Tissue was stained using the Anti-Sheep HRP-DAB Cell & Tissue Staining Kit (brown; Catalog # CTS019) and counterstained with hematoxylin (blue). Specific staining was localized to the brush border in intestinal epithelium. View our protocol for Chromogenic IHC Staining of Frozen Tissue Sections.|
Serpin A8 (serine proteinase inhibitor-clade A8; also angiotensinogen) is a secreted, 52-62 kDa glycoprotein member of the clade F-subfamily, serpin superfamily of protease inhibitors. It is expressed by neurons and hepatocytes, and undergoes extracellular cleavage by renin to create a ten amino acid (aa) peptide termed Ang/angiotensin I. This inactive peptide is further cleaved by ACE on the endothelial cell membrane to create bioactive Ang II and III. Ang II induces vascoconstriction and aldosterone release by acting on AT1 receptors, while Ang III drives aldosterone release. Ang I can be further processed by MME to generate Ang, a peptide that binds MAS1 on platelets, and promotes the release of NO, an antithrombotic agent. Mature mouse angiotensinogen is 453 aa in length (aa 25-477). It contains Ang I (aa 25-34) that is cleaved to create Ang II (aa 25-32), Ang III (aa 26-32) and Ang I (aa 25-31). Serpin A8/Angiotensinogen may circulate in a 200 kDa complex with major basic protein (MBP), or as part of a larger 300 kDa complex with MBP and complement C3dg. There is an alternative start site five aa upstream of the standard site. Over aa 25-477, mouse serpin A8 shares 86% and 61% aa identity with rat and human serpin A8, respectively.