Proteolysis of histidine-rich glycoprotein in plasma and in patients undergoing thrombolytic therapy

Smith, Ann; Nuiry, Ileana I.; Morgan, William T.

doi:10.1016/0049-3848(85)90303-2

Cited by 21 publications

(21 citation statements)

References 23 publications

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“…Silver staining of SDSpolyacrylamide gels of HRGk75 revealed mostly 75-kDa protein and small amounts of 50-kDa material, while analysis of Celsus HRG revealed much less 75-kDa material and bands at 67, 50, 48, and 40 kDa (Fig. 1A), which are consistent with earlier biochemical studies of this molecule (27). Western blotting with monoclonal antibody to HRG revealed reactivity with the 75-, 67-, 50-, 48-, and 40-kDa bands (Fig.…”

Section: Resultssupporting

confidence: 80%

“…Analysis of the commercial HRG by silver staining and Western blotting techniques under reducing conditions showed major bands corresponding to previously reported native and cleaved forms of 75, 63, 50, and Ͻ 50 kDa (27). The N-terminal region of HRG shares a high degree of sequence homology with the N-terminal region of antithrombin, as well as critical lysine and arginine residues which are essential for heparin binding (32)(33)(34).…”

Section: Discussionmentioning

confidence: 97%

“…The Effect of Zinc on Heparin Activity-The interaction between heparin and HRG has been reported to require divalent cations (2,5,27). We studied the differential effects of zinc on thrombin-mediated fibrinogenesis in citrated and citrated/heparinized plasmas and found that the thrombin times of citrated plasmas were not changed by supplemental zinc but that the thrombin times of citrated/heparinized plasmas were shortened in a dose-dependent manner (Fig.…”

Section: Resultsmentioning

confidence: 99%

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Zinc as a Cofactor for Heparin Neutralization by Histidine-rich Glycoprotein

Kluszynski

Kim

Faulk

1997

Journal of Biological Chemistry

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We have studied the ability of histidine-rich glycoprotein (HRG) to neutralize the anticoagulant activity of heparin in plasma and in a purified component clotting assay. Addition of HRG to plasma or to the purified component assay did not neutralize the anticoagulant activity of heparin unless micromolar concentrations of zinc were present. Higher zinc concentrations were required for citrated than for heparinized plasmas due to competition of citrate with HRG for zinc binding. Zinc concentrations as low as 1.25 M revealed HRG to be a powerful competitor of antithrombin for heparin in the purified component assays. HRG binding of heparin also was shown by affinity chromatography of HRG from immobilized heparin in the presence and absence of zinc. In the absence of zinc, HRG was eluted by 0.1 M NaCl, but, in the presence of zinc, elution of HRG required 1.0 M NaCl. Investigation of other divalent cations (copper and magnesium) indicated that augmentation of heparin binding by HRG in the presence of antithrombin was restricted to zinc. The HRG⅐Zn complex effectively competes with antithrombin for heparin, which restricts the availability of heparin to bind antithrombin and allows thrombin-mediated fibrinogenesis to proceed unimpeded. This could be initiated by zinc released from activated platelets.

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Section: Resultssupporting

confidence: 80%

Section: Discussionmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

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Zinc as a Cofactor for Heparin Neutralization by Histidine-rich Glycoprotein

Kluszynski

Kim

Faulk

1997

Journal of Biological Chemistry

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“…Sequencing of the naturally occurring His/Pro-rich peptide should provide additional data on which protease is involved in its in vivo generation and hence additional information on its regulation. Plasmin and kallikrein are two serine proteases previously shown to have the capacity to cleave purified HRG in vitro (30). One possibility is also that platelet activation creates an environment that favors activation of a proteolytic enzyme involved in generation of the His/Pro-rich fragment.…”

Section: Discussionmentioning

confidence: 99%

Activated Platelets Provide a Functional Microenvironment for the Antiangiogenic Fragment of Histidine-Rich Glycoprotein

Thulin

Ringvall

Dimberg

et al. 2009

Molecular Cancer Research

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“…These immunoreactive bands, however, were present even in human milk and colostrum collected with reportedly adequate concentrations of protease inhibitors (9, 34,35). Very similar HRG degradation products have been observed after treatment of purified plasma HRG with plasmin or trypsin (8, 34).…”

Section: Discussionmentioning

confidence: 98%

Identification of Histidine-Rich Glycoprotein in Human Colostrum and Milk

1992

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ABSTRACT. Histidine-rich glycoprotein (HRG) is a 74-kD glycoprotein, originally discovered in plasma, which contains an unusually large amount of histidine (13 mol%) and proline (13 mol%). The specific functions of this protein remain unclear, although it binds (reversibly) transition metal ions such as Cu(I1) and Zn(1I) with high capacity (10-13 equivalent) and moderate to high affinity (h = 0.2-10 pM). Because the bioavailability of Cu (I1) and Zn(I1) ions in human milk is high, we have used specific antibodies from polyclonal antisera directed against purified human plasma HRG to investigate whether this or a related protein is a component of human colostrum and(or) mature milk. Fresh human colostrum (d 1-3) and milk (d 4-120) were collected in the presence and absence of multiple protease inhibitors and EDTA. Immuno "dot" blot analyses and ELISA were developed; HRG was present in both colostrum (0.13-10 pg/mL) and mature milk (0.1-10 pg/mL). Unidentified components in colostrum and milk, however, were found to depress HRG antigenicity in these assays. Western transfer and immunoblots of denatured colostrum and milk samples analyzed by SDS-PAGE revealed the presence of an immunoreactive band at 74-78 kD, with other bands at 47 and 24 kD under both reducing and nonreducing conditions; smaller immunoreactive fragments (12-14 kD) were detected in some samples. We observed at least one additional band of immunoreactivity of greater molecular mass (>I10 kD) in colostrum under nonreducing conditions; we did not observe these bands in plasma samples. Immunoaffinity and Zn(I1) affinity isolation of HRG from colostrum and milk resulted in the copurification of several associated proteins. Nterminal amino acid sequence analysis of the isolated 74-kD immunoreactive protein provided further evidence for identification as intact HRG; 13 of the first 15 residues were identical. These results demonstrate the presence of HRG, or a structurally related protein, in human colostrum and milk. Understanding the biology and function of trace elements in human. milk must include the identification of specific human milk peptides and proteins that influence metal ion transport (bioavailability) and storage in the mammary gland during lactogenesis, as well as in the gastrointestinal tract of breast-fed infants. Equally important, in our view, is the need to understand the role of transition metal ions in the regulation of milk protein structure, bioavailability, and function. Much can be learned from existing knowledge of the transport and use of transition metal ions by serum proteins. For example, in several species, including humans, many of the proteins in maternal serum, particularly the metal-binding proteins, are similar or identical to the whey proteins in colostrum (1,2).Adult human serum contains a protein discovered in 1972 (3) referred to as histidine-rich glycoprotein.' HRG is a 74-kD glycoprotein that contains significant quantities of both histidine (13%) and proline (13%) (4), which are concentrated primarily in the C...

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Proteolysis of histidine-rich glycoprotein in plasma and in patients undergoing thrombolytic therapy

Cited by 21 publications

References 23 publications

Zinc as a Cofactor for Heparin Neutralization by Histidine-rich Glycoprotein

Zinc as a Cofactor for Heparin Neutralization by Histidine-rich Glycoprotein

Activated Platelets Provide a Functional Microenvironment for the Antiangiogenic Fragment of Histidine-Rich Glycoprotein

Identification of Histidine-Rich Glycoprotein in Human Colostrum and Milk

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