InnateDB: Systems Biology of the Innate Immune Response

Homo sapiens Protein: HP

Summary

InnateDB Protein

IDBP-233821.7

Last Modified

2014-10-13 [Report errors or provide feedback]

Gene Symbol

Protein Name

haptoglobin

Synonyms

BP; HP2ALPHA2; HPA1S;

Species

Homo sapiens

Ensembl Protein

ENSP00000381199

InnateDB Gene

IDBG-547150 (HP)

Protein Structure

UniProt Annotation

Function

As a result of hemolysis, hemoglobin is found to accumulate in the kidney and is secreted in the urine. Haptoglobin captures, and combines with free plasma hemoglobin to allow hepatic recycling of heme iron and to prevent kidney damage. Haptoglobin also acts as an Antimicrobial; Antioxidant, has antibacterial activity and plays a role in modulating many aspects of the acute phase response. Hemoglobin/haptoglobin complexes are rapidely cleared by the macrophage CD163 scavenger receptor expressed on the surface of liver Kupfer cells through an endocytic lysosomal degradation pathway. {ECO:0000269PubMed:21248165}.Uncleaved haptoglogin, also known as zonulin, plays a role in intestinal permeability, allowing intercellular tight junction disassembly, and controlling the equilibrium between tolerance and immunity to non-self antigens. {ECO:0000269PubMed:21248165}.

Subcellular Localization

Secreted.

Disease Associations

Anhaptoglobinemia (AHP) [MIM:614081]: A condition characterized by the absence of the serum glycoprotein haptoglobin. Serum levels of haptoglobin vary among normal persons: levels are low in the neonatal period and in the elderly, differ by population, and can be influenced by environmental factors, such as infection. Secondary hypohaptoglobinemia can occur as a consequence of hemolysis, during which haptoglobin binds to free hemoglobin. Congenital haptoglobin deficiency is a risk factor for anaphylactic non-hemolytic transfusion reactions. {ECO:0000269PubMed:14999562}. Note=The disease is caused by mutations affecting the gene represented in this entry.

Tissue Specificity

Expressed by the liver and secreted in plasma.

Comments

Interactions

Number of Interactions

This gene and/or its encoded proteins are associated with 21 experimentally validated interaction(s) in this database.

Experimentally validated
Total	21 [view]
Protein-Protein	20 [view]
Protein-DNA	0
Protein-RNA	1 [view]
DNA-DNA	0
RNA-RNA	0
DNA-RNA	0

Gene Ontology

Molecular Function

Accession	GO Term
GO:0003824	catalytic activity
GO:0004252	serine-type endopeptidase activity
GO:0005515	protein binding
GO:0016209	antioxidant activity
GO:0030492	hemoglobin binding

Biological Process

GO:0002376	immune system process
GO:0006508	proteolysis
GO:0006952	defense response
GO:0006953	acute-phase response
GO:0008152	metabolic process
GO:0010942	positive regulation of cell death
GO:0042542	response to hydrogen peroxide
GO:0042742	defense response to bacterium
GO:0051354	negative regulation of oxidoreductase activity
GO:2000296	negative regulation of hydrogen peroxide catabolic process

Cellular Component

GO:0005576	extracellular region
GO:0005615	extracellular space
GO:0031838	haptoglobin-hemoglobin complex
GO:0070062	extracellular vesicular exosome
GO:0071682	endocytic vesicle lumen
GO:0072562	blood microparticle

Protein Structure and Domains

PDB ID

InterPro

IPR000436 Sushi/SCR/CCP
IPR001254 Peptidase S1
IPR001314 Peptidase S1A, chymotrypsin-type
IPR008292 Haptoglobin
IPR009003 Trypsin-like cysteine/serine peptidase domain

PFAM

PF00084
PF00089

PRINTS

PR00722

PIRSF

PIRSF001137

SMART

SM00032
SM00020

TIGRFAMs

Post-translational Modifications

Modification

Cross-References