Hemopexin (or haemopexin; Hpx; Hx), also known as beta-1B-glycoprotein, is a glycoprotein that in humans is encoded by the HPX gene and belongs to the hemopexin family of proteins. Hemopexin is the plasma protein with the highest binding affinity for heme. Hemoglobin itself circulating alone in the blood plasma (called free hemoglobin, as opposed to the hemoglobin situated in and circulating with the red blood cell.) will soon be oxidized into met-hemoglobin which then further disassociates into free heme along with globin chain. The free heme will then be oxidized into free met-heme and sooner or later the hemopexin will come to bind free met-heme together, forming a complex of met-heme and hemopexin, continuing their journey in the circulation until reaching a receptor, such as LRP1, on hepatocytes or macrophages within the spleen, liver and bone marrow. Hemopexin's arrival and subsequent binding to the free heme not only prevent heme's pro-oxidant and pro-inflammatory effects but also promotes free heme's detoxification. Hemopexin is different from haptoglobin, the latter always binds to free hemoglobin.
Background References
1. Nakagiri T et al. Hemopexin alleviates sterile inflammation in ischemia-reperfusion-induced lung injury. Front Immunol. 2024 Oct
2. Li Y et al. Double-edged functions of hemopexin in hematological related diseases: from basic mechanisms to clinical application. Front Immunol. 2023 Nov
Sequence Similarity
Belongs to the hemopexin family.
Tissue Specificity
Expressed by the liver and secreted in plasma.
Post-translational Modification
N- and O-glycosylated. O-glycosylated with core 1 or possibly core 8 glycans. O-glycosylation in the 30-40 region is minor compared to glycosylation at Thr-24 and Thr-29.
Western blot analysis of Hemopexin on human liver tissue lysates with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/500 dilution.
Lysates/proteins at 20 µg/Lane.
Predicted band size: 52 kDa Observed band size: 70 kDa
Exposure time: 2 minutes;
8% SDS-PAGE gel.
Proteins were transferred to a PVDF membrane and blocked with 5% NFDM/TBST for 1 hour at room temperature. The primary antibody (ET1706-10) at 1/500 dilution was used in 5% NFDM/TBST at room temperature for 2 hours. Goat Anti-Rabbit IgG - HRP Secondary Antibody (HA1001) at 1:300,000 dilution was used for 1 hour at room temperature.
Immunocytochemistry analysis of HepG2 cells labeling Hemopexin with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution.
Cells were fixed in 4% paraformaldehyde for 10 minutes at 37 ℃, permeabilized with 0.05% Triton X-100 in PBS for 20 minutes, and then blocked with 2% negative goat serum for 30 minutes at room temperature. Cells were then incubated with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution in 2% negative goat serum overnight at 4 ℃. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution.Nuclear DNA was labelled in blue with DAPI.
IImmunocytochemistry analysis of LO2 cells labeling Hemopexin with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution.
Cells were fixed in 4% paraformaldehyde for 10 minutes at 37 ℃, permeabilized with 0.05% Triton X-100 in PBS for 20 minutes, and then blocked with 2% negative goat serum for 30 minutes at room temperature. Cells were then incubated with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution in 2% negative goat serum overnight at 4 ℃. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution.Nuclear DNA was labelled in blue with DAPI.
Immunocytochemistry analysis of LOVO cells labeling Hemopexin with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution.
Cells were fixed in 4% paraformaldehyde for 10 minutes at 37 ℃, permeabilized with 0.05% Triton X-100 in PBS for 20 minutes, and then blocked with 2% negative goat serum for 30 minutes at room temperature. Cells were then incubated with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution in 2% negative goat serum overnight at 4 ℃. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution.Nuclear DNA was labelled in blue with DAPI.
Immunocytochemistry analysis of SK-Br-3 cells labeling Hemopexin with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution.
Cells were fixed in 4% paraformaldehyde for 10 minutes at 37 ℃, permeabilized with 0.05% Triton X-100 in PBS for 20 minutes, and then blocked with 2% negative goat serum for 30 minutes at room temperature. Cells were then incubated with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution in 2% negative goat serum overnight at 4 ℃. Alexa Fluor®488 conjugate-Goat anti-Rabbit IgG was used as the secondary antibody at 1/1,000 dilution. Nuclear DNA was labelled in blue with DAPI.
Immunohistochemical analysis of paraffin-embedded human liver tissue with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (ET1706-10) at 1/50 dilution for 0.5 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
Immunohistochemical analysis of paraffin-embedded human placenta tissue with Rabbit anti-Hemopexin antibody (ET1706-10) at 1/50 dilution.
The section was pre-treated using heat mediated antigen retrieval with Tris-EDTA buffer (pH 9.0) for 20 minutes. The tissues were blocked in 1% BSA for 20 minutes at room temperature, washed with ddH2O and PBS, and then probed with the primary antibody (ET1706-10) at 1/50 dilution for 0.5 hour at room temperature. The detection was performed using an HRP conjugated compact polymer system. DAB was used as the chromogen. Tissues were counterstained with hematoxylin and mounted with DPX.
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