Histidine-rich Glycoprotein (human, recombinant)

Histidine-rich glycoprotein is an abundant plasma glycoprotein that is involved in diverse biological processes, including angiogenesis, hemostasis, cell adhesion, and immunity.^1,2 It is composed of a signal peptide and two cystatin-like regions in the N-terminal domain, a central domain with a histidine-rich region (HRR) and two proline-rich regions (PRRs) on either side, and a C-terminal domain. Histidine-rich glycoprotein is mainly produced by the liver but is also found in platelets and megakaryocytes.^3,4 It has many binding partners, including IgG, immunoglobulin γ receptor (FcγR), and complement 1q (C1q), which bind to the N-terminal domain, zinc, heme, and microbes, which bind to the HRR, heparin and heparan sulfate, which bind to the N-terminal domain and HRR, plasminogen and thrombospondin, which bind to the N-terminal and C-terminal domains, and phospholipids, fibrinogen, and complement components, which have undefined binding regions.² Histidine-rich glycoprotein is also able to bind to various cell types such as T cells, B cells, erythrocytes, endothelial cells, and several cancer types. It modulates macrophage polarization, facilitates the clearance of apoptotic and necrotic cells, promotes antitumor immunity, and has antibacterial and antiviral activities.^1,2 Overexpression of HRG decreases tumor burden, metastasis, hypoxia, and blood vessel density and increases tumor-associated macrophage (TAM) accumulation in several mouse xenograft models.⁵ Increased plasma levels of histidine-rich glycoprotein are associated with the development of post-thrombotic syndrome following a venous thromboembolic event (VTE).⁶ Cayman's Histidine-rich Glycoprotein (human, recombinant) protein can be used for cell-based adhesion assays. This protein consists of 518 amino acids, has a calculated molecular weight of 59 kDa, and a predicted N-terminus of Val19 after signal peptide cleavage. By SDS-PAGE, under reducing conditions, the apparent molecular mass of the protein is 75-80 kDa due to glycosylation.

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1. Pan, Y., Deng, L., Wang, H., et al. Histidine-rich glycoprotein (HRGP): Pleiotropic and paradoxical effects on macrophage, tumor microenvironment, angiogenesis, and other physiological and pathological processes. Genes Dis. 9(2), 381-392 (2022).

2. Poon, I.K.H., Patel, K.K., Davis, D.S., et al. Histidine-rich glycoprotein: the Swiss Army knife of mammalian plasma. Blood 117(7), 2093-2101 (2011).

3. Koide, T., Foster, D., Yoshitake, S., et al. Amino acid sequence of human histidine-rich glycoprotein derived from the nucleotide sequence of its cDNA. Biochemistry 25(8), 2220-2225 (1986).

4. Leung, L.L.K., Harpel, P.C., Nachman, R.L., et al. Histidine-rich glycoprotein is present in human platelets and is released following thrombin stimulation. Blood 62(5), 1016-1021 (1983).

5. Rolny, C., Mazzone, M., Tugues, S., et al. HRG inhibits tumor growth and metastasis by inducing macrophage polarization and vessel normalization through downregulation of PlGF. Cancer Cell 19(1), 31-44 (2011).

6. Siudut, J., Natorska, J., Son, M., et al. Increased levels of histidine‑rich glycoprotein are associated with the development of post‑thrombotic syndrome. Sci. Rep. 10(1), 14419 (2020).