Haptoglobin

HP
Available structures
PDB	Ortholog search: PDBe RCSB
List of PDB id codes
	4X0L, 4WJG, 5HU6
Identifiers
Aliases	HP, BP, HP2ALPHA2, HPA1S, haptoglobin
External IDs	OMIM: 140100; MGI: 96211; HomoloGene: 121756; GeneCards: HP; OMA:HP - orthologs
Gene location (Human)
Chr.	Chromosome 16 (human)
End	72,061,055 bp
Gene location (Mouse)
Chr.	Chromosome 8 (mouse)
End	110,305,804 bp
RNA expression pattern
	Top expressed in
	pericardium; ; right lobe of liver; ; olfactory zone of nasal mucosa; ; parietal pleura; ; bone marrow; ; germinal epithelium; ; bone marrow cells; ; trabecular bone; ; peritoneum; ; vena cava;
	Top expressed in
	lacrimal gland; ; gallbladder; ; left lobe of liver; ; granulocyte; ; right lung lobe; ; stroma of bone marrow; ; white adipose tissue; ; subcutaneous adipose tissue; ; tunica adventitia of aorta; ; tibiofemoral joint;
	More reference expression data
	More reference expression data
Gene ontology
Molecular function	antioxidant activity; protein binding; hemoglobin binding; serine-type endopeptidase activity;
Cellular component	extracellular region; endocytic vesicle lumen; extracellular exosome; blood microparticle; haptoglobin-hemoglobin complex; extracellular space; specific granule lumen; tertiary granule lumen;
Biological process	cellular oxidant detoxification; defense response; positive regulation of cell death; acute-phase response; receptor-mediated endocytosis; defense response to bacterium; response to hydrogen peroxide; negative regulation of oxidoreductase activity; negative regulation of hydrogen peroxide catabolic process; immune system process; neutrophil degranulation; acute inflammatory response; proteolysis; response to organic substance;
	Sources:Amigo / QuickGO
Orthologs
	3240
	15439
	ENSG00000257017
	ENSMUSG00000031722
	P00738
	Q61646
	NM_001126102; NM_005143; NM_001318138
	NM_017370; NM_001329965
	NP_001119574; NP_001305067; NP_005134
	NP_001316894; NP_059066
	Wikidata
View/Edit Human	View/Edit Mouse

Haptoglobin (abbreviated as Hp) is the protein that in humans is encoded by the HP gene. In blood plasma, haptoglobin binds with high affinity to free hemoglobin released from erythrocytes, and thereby inhibits its deleterious oxidative activity. Compared to Hp, hemopexin binds to free heme. The haptoglobin-hemoglobin complex will then be removed by the reticuloendothelial system (mostly the spleen).

In clinical settings, the haptoglobin assay is used to screen for and monitor intravascular hemolytic anemia. In intravascular hemolysis, free hemoglobin will be released into circulation and hence haptoglobin will bind the hemoglobin. This causes a decline in haptoglobin levels.

The protein was discovered as a "plasma substance" in 1938 by French biochemists Max-Fernand Jayle and Michel Polonovski.