|Detection of Mouse Hemopexin by Western Blot. Western blot shows mouse plasma. PVDF membrane was probed with 2 µg/mL of Rat Anti-Mouse Hemopexin Monoclonal Antibody (Catalog # MAB7007) followed by HRP-conjugated Anti-Rat IgG Secondary Antibody (Catalog # HAF005). A specific band was detected for Hemopexin at approximately 65-75 kDa (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 1.|
HPX (Hemopexin) is a 60-68 kDa secreted member of the hemopexin family of molecules. Although it is principally expressed by hepatocytes, it is also reportedly secreted by macrophages, neurons, astrocytes, renal mesangial cells and fibroblasts. It is considered an acute phase protein, and demonstrates a number of effects. Principally, it binds free and albumin-bound heme, neutralizing its potential for oxidative damage to cell membranes. Heme is removed from HPX internally following binding of the HPX:heme complex to CD91 on hepatocytes and macrophages. HPX also dampens the proinflammatory response of macrophages to TLR2 and TLR4 activation. And HPX also shows serine protease activity which may impact cell surface proteins and ECM. Mature mouse HPX is a 437 amino acid (aa) glycoprotein (aa 24-460). It contains five consecutive HPX-like domains (aa 56-349) that likely impart binding-partner specificity to HPX. There are multiple potential isoform variants. One shows a two aa substitution for aa 134-460, a second contains a deletion of aa 60-100, a third possesses a 14 aa substitution for aa 235-460, while a fourth shows a two aa substitution for aa 153-460. Mature mouse HPX shares 92% and 77% aa identity with rat and human HPX, respectively.