Mouse HPRG Biotinylated Antibody

Mouse histidine-rich glycoprotein (HPRG) is a multidomain, monomeric, secreted, 67‑75 kDa member of the cystatin superfamily of molecules (1, 2). Its name derives from the fact that 22% of its amino acids (aa) are histidine and proline. In mouse, it is synthesized as a 525 amino acid (aa) precursor that contains an 18 aa signal sequence and a 507 aa mature region (3). Five distinct domains are recognized in the mature molecule. There are two N-terminal cystatin-like modules and one His-Pro-rich region that is flanked by two Pro-rich segments (3, 4). The His-Pro-rich region contains multiple tandem repeats with a GHHPH motif, while the N- and C‑termini are linked by a disulfide bond (3, 5, 6). Mouse HPRG is only 60% aa identical to human HPRG, and 79% aa identical to rat HPRG. There are multiple ligands for HPRG. These include small molecular weight molecules (metal ions; heme), hemostatic molecules (heparan sulfate; TSP; plasminogen), and immune system components (T cells; macrophages) (1, 5). About 50% of plasma plasminogen circulates bound to HPRG. Upon immobilization to cell surface tropomyosin in a Zn⁺⁺‑dependent manner, it is converted to plasmin by tPA (7‑9). HPRG also shows antiangiogenic activity on endothelial cells (10). Finally, it binds to cytoplasmic ligand(s) exposed during cellular necrosis, and facilitates macrophage phagocytosis (11).