Details for: HP

Gene ID: 3240

Gene Type:  Protein-coding  - A gene that serves as a template for producing a messenger RNA (mRNA) molecule, which is then translated into a functional protein.

Symbol: HP

Ensembl ID: ENSG00000257017

Description: haptoglobin

Selected Context(s):  Overall

Cell Significance Landscape

Contexts:

Associated with

Significant Cells

Cell Significance Index (CSI) scores for the chosen context(s)

  • hepatocyte CL0000182
    CSI 25.5
    rCSI 45.64%
    PRS 96.22
  • centrilobular region hepatocyte CL0019029
    CSI 17.23
    rCSI 44.96%
    PRS 94.81
  • epithelial cell of lower respiratory tract CL0002632
    CSI 15.6
    rCSI 12.1%
    PRS 98.71
  • midzonal region hepatocyte CL0019028
    CSI 13.45
    rCSI 31.56%
    PRS 95.5
  • alveolar macrophage CL0000583
    CSI 12.93
    rCSI 21.3%
    PRS 97.94
  • periportal region hepatocyte CL0019026
    CSI 9.31
    rCSI 36.2%
    PRS 95.09
  • promonocyte CL0000559
    CSI 9.04
    rCSI 15.48%
    PRS 98.3
  • regulatory T cell CL0000815
    CSI 7.72
    rCSI 8.95%
    PRS 92.57
  • intrahepatic cholangiocyte CL0002538
    CSI 7.29
    rCSI 17.48%
    PRS 97.25
  • mature NK T cell CL0000814
    CSI 6.73
    rCSI 8.61%
    PRS 98.3
  • innate lymphoid cell CL0001065
    CSI 6.65
    rCSI 13.72%
    PRS 92.75
  • epicardial adipocyte CL1000309
    CSI 6.55
    rCSI 21.31%
    PRS 96.11
  • neutrophil CL0000775
    CSI 5.21
    rCSI 29.13%
    PRS 95.49
  • helper T cell CL0000912
    CSI 5.1
    rCSI 7.21%
    PRS 93.31
  • serous secreting cell CL0000313
    CSI 4.62
    rCSI 23.37%
    PRS 98.1
  • mesenchymal stem cell of adipose tissue CL0002570
    CSI 3.97
    rCSI 22.15%
    PRS 98.35
  • hepatic stellate cell CL0000632
    CSI 3.64
    rCSI 13.64%
    PRS 96.44
  • alveolar adventitial fibroblast CL4028006
    CSI 3.41
    rCSI 5.39%
    PRS 98.34
  • Kupffer cell CL0000091
    CSI 3.01
    rCSI 6.89%
    PRS 98.01
  • CD8-positive, alpha-beta memory T cell, CD45RO-positive CL0001203
    CSI 2.9
    rCSI 3.52%
    PRS 84.54
  • endothelial cell of periportal hepatic sinusoid CL0019021
    CSI 2.89
    rCSI 13.24%
    PRS 97.92
  • adipocyte CL0000136
    CSI 2.47
    rCSI 3.18%
    PRS 94.01
  • erythrocyte CL0000232
    CSI 2.33
    rCSI 5.28%
    PRS 96.25
  • endothelial cell of pericentral hepatic sinusoid CL0019022
    CSI 2.11
    rCSI 6.52%
    PRS 98.06
  • basal cell of epidermis CL0002187
    CSI 2.11
    rCSI 3.74%
    PRS 78.94
  • cytotoxic T cell CL0000910
    CSI 1.28
    rCSI 7.31%
    PRS 94.83
  • myelocyte CL0002193
    CSI 1.13
    rCSI 7.45%
    PRS 98.78

Cell ID: Standard Cell Ontology term used for mapping and comparing cells across experiments. Ensures consistency in analyzing cellular functions across tissues.
Fold Change: Represents the ratio of the current Cell Significance Index to the Cell Significance Index Threshold, indicating how much the gene expression has changed compared to a baseline.
Cell Significance Index: Reflects how strongly a gene is expressed in this specific cell.

Cell ID: Standard Cell Ontology term used for mapping and comparing cells across experiments. Ensures consistency in analyzing cellular functions across tissues.
Fold Change: Represents the ratio of the current Cell Significance Index to the Cell Significance Index Threshold, indicating how much the gene expression has changed compared to a baseline.
Cell Significance Index: Reflects how strongly a gene is expressed in this cell type. Calculated using techniques like effect size estimation and bootstrapping for reliability.

Cell ID: Standard Cell Ontology term used for mapping and comparing cells across experiments. Ensures consistency in analyzing cellular functions across tissues.
Fold Change: Represents the ratio of the current Cell Significance Index to the Cell Significance Index Threshold, indicating how much the gene expression has changed compared to a baseline.
Cell Significance Index: Reflects how strongly a gene is expressed in this cell type. Calculated using techniques like effect size estimation and bootstrapping for reliability.
Network Configuration

Explore relationships of the current gene. Select an Interaction Source: 'ONTOLOGY' for shared pathways (GO/Reactome) or 'STRING' for protein-protein interactions. Further refine by selecting context genes and comparing Cell Significance Index (CSI) scores between baseline and target cell types and their specific contexts.

Comma-separated if multiple.
Comma-separated if multiple.

Legend:
  • Query Gene
  • Node Color (Target Cell CSI, relative to current network):
    • Very High
    • High
    • Medium
    • Low
    • Very Low
    • CSI N/A
  • Node Size: Proportional to Target Cell CSI magnitude
  • STRING PPI Edge
  • Shared Pathway Edge (ONTOLOGY)

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Other Information

This section provides additional information about the gene, including a description generated by an AI language model and details about associated proteins.

## Summary [HP](/details-gene/3240), or haptoglobin, is a protein-coding gene located on chromosome 16q22.2. It encodes a plasma glycoprotein that functions as a key acute-phase reactant. The primary role of haptoglobin is to bind free hemoglobin released from erythrocytes, thereby preventing iron loss and protecting tissues from the oxidative damage caused by free heme. Its synthesis is predominantly carried out by [hepatocyte](/details-cell/CL0000182)s, which is reflected in its exceptionally high expression significance in these cells. Beyond its canonical role in heme scavenging, [HP](/details-gene/3240) is involved in the innate immune response and antioxidant defense mechanisms. Clinically, genetic variants and plasma levels of haptoglobin are associated with susceptibility to and severity of various inflammatory, infectious, and cardiovascular diseases, as noted in OMIM ([140100](https://omim.org/entry/140100)). ## Cellular Roles and Expression Landscape The expression profile of [HP](/details-gene/3240) in the **Overall** context firmly establishes it as a hepatically-derived plasma protein, while also highlighting significant roles in other tissues and the immune system. * **Hepatic Dominance:** The gene shows its highest significance in liver cells, including [hepatocyte](/details-cell/CL0000182) (CSI: 25.50), [centrilobular region hepatocyte](/details-cell/CL0019029) (CSI: 17.23), [midzonal region hepatocyte](/details-cell/CL0019028) (CSI: 13.45), and [periportal region hepatocyte](/details-cell/CL0019026) (CSI: 9.31). This is consistent with the liver being the primary site of synthesis for circulating haptoglobin. Its expression in [intrahepatic cholangiocyte](/details-cell/CL0002538)s further underscores its importance within the liver microenvironment. * **Respiratory and Secretory Tissues:** A striking finding is the high significance of [HP](/details-gene/3240) in [epithelial cell of lower respiratory tract](/details-cell/CL0002632) (CSI: 15.60), suggesting a crucial role for local synthesis in pulmonary host defense and management of inflammation. Significant expression is also noted in [serous secreting cell](/details-cell/CL0000313)s, indicating its presence in exocrine secretions. * **Myeloid and Innate Immune System:** [HP](/details-gene/3240) is a significant marker in several myeloid lineage cells, including [alveolar macrophage](/details-cell/CL0000583) (CSI: 12.93), [promonocyte](/details-cell/CL0000559) (CSI: 9.04), and [neutrophil](/details-cell/CL0000775) (CSI: 5.21). This pattern aligns with its function in the innate immune response, where it may contribute to pathogen defense and the clearance of cellular debris at sites of inflammation. * **Lymphoid Cell Involvement:** The data also suggest a potential role for [HP](/details-gene/3240) in the adaptive immune system, with notable significance in [regulatory T cell](/details-cell/CL0000815) (CSI: 7.72), [mature NK T cell](/details-cell/CL0000814) (CSI: 6.73), [innate lymphoid cell](/details-cell/CL0001065) (CSI: 6.65), and [helper T cell](/details-cell/CL0000912) (CSI: 5.10). This expression may indicate an immunomodulatory function beyond its primary scavenging duties. ## Pathways and Molecular Function The functional annotations for [HP](/details-gene/3240) are highly consistent with its established biological roles. Its involvement in the `Acute-phase response` ([GO:0006953](https://www.ebi.ac.uk/QuickGO/term/GO:0006953)) explains its upregulation during inflammation. The core molecular function is `Hemoglobin binding` ([GO:0030492](https://www.ebi.ac.uk/QuickGO/term/GO:0030492)), which is central to the Reactome pathway `Scavenging of heme from plasma` ([R-HSA-2168880](https://reactome.org/content/detail/R-HSA-2168880)). This action directly contributes to `Cellular oxidant detoxification` ([GO:0098869](https://www.ebi.ac.uk/QuickGO/term/GO:0098869)) and confers `Antioxidant activity` ([GO:0016209](https://www.ebi.ac.uk/QuickGO/term/GO:0016209)) by sequestering redox-active iron. The gene's role in the immune system is highlighted by its association with the `Innate immune system` ([R-HSA-168249](https://reactome.org/content/detail/R-HSA-168249)) and `Defense response to bacterium` ([GO:0042742](https://www.ebi.ac.uk/QuickGO/term/GO:0042742)). Its presence in the `Specific granule lumen` ([GO:0035580](https://www.ebi.ac.uk/QuickGO/term/GO:0035580)) of immune cells is consistent with its involvement in `Neutrophil degranulation` ([R-HSA-6798695](https://reactome.org/content/detail/R-HSA-6798695)), suggesting it is a pre-packaged component of the rapid immune response. Interestingly, haptoglobin is also annotated with `Serine-type endopeptidase activity` ([GO:0004252](https://www.ebi.ac.uk/QuickGO/term/GO:0004252)), reflecting its evolutionary origin as a serine protease homolog, a structural feature confirmed by early research ([Link](https://pubmed.ncbi.nlm.nih.gov/6997877/)). ## Research Directions The expression profile of [HP](/details-gene/3240) suggests several avenues for future investigation, particularly regarding its localized functions outside the liver. **Testable Hypotheses:** 1. **Localized Pulmonary Defense:** The high significance of [HP](/details-gene/3240) in [epithelial cell of lower respiratory tract](/details-cell/CL0002632) suggests that locally secreted haptoglobin is a critical first-line defense mechanism in the lungs. We hypothesize that epithelial-derived haptoglobin protects against oxidative stress and microbial invasion during lung injury or infection, and its deficiency exacerbates inflammatory lung diseases. 2. **Immunomodulation of T Cells:** The expression of [HP](/details-gene/3240) in lymphoid populations like [regulatory T cell](/details-cell/CL0000815)s suggests a direct role in adaptive immunity. We hypothesize that the haptoglobin-hemoglobin complex, or haptoglobin itself, interacts with scavenger receptors (like CD163) on T cells or antigen-presenting cells to modulate T cell activation, proliferation, or suppressive function in an iron-dependent manner. **Proposed Experimental Approach:** To test the hypothesis regarding the role of [HP](/details-gene/3240) in localized pulmonary defense, a key experiment would involve the use of a lung epithelial-specific conditional knockout mouse model (e.g., Sftpc-Cre;Hp-flox/flox). These mice, along with wild-type controls, would be subjected to an inflammatory challenge such as intratracheal administration of lipopolysaccharide (LPS) or infection with *Streptococcus pneumoniae*. The impact of local haptoglobin deficiency could be assessed by quantifying inflammatory cell infiltration into the bronchoalveolar lavage fluid (BALF) via flow cytometry, measuring cytokine levels (e.g., IL-6, TNF-alpha) by ELISA, and evaluating lung tissue damage and oxidative stress markers (e.g., 8-OHdG) through histology and biochemical assays. **Therapeutic Potential:** [HP](/details-gene/3240) is not a target for inhibition but rather a candidate for **augmentation or replacement therapy**. Its primary function is protective, and low levels are associated with poor outcomes in conditions involving significant intravascular hemolysis (e.g., sickle cell disease, malaria, complications from blood transfusions or cardiac surgery). Purified or recombinant haptoglobin could be administered therapeutically to sequester toxic free hemoglobin, thereby preventing acute kidney injury and systemic endothelial dysfunction. This strategy aims to restore a natural defense mechanism rather than inhibit a pathological process.

Genular Protein ID: 963343575

Symbol: HPT_HUMAN

Name: Haptoglobin

UniProtKB Accession Codes:

Database IDs:

Citations:

PubMed ID: 6688992

Title: Molecular cloning of human haptoglobin cDNA: evidence for a single mRNA coding for alpha 2 and beta chains.

PubMed ID: 6688992

DOI: 10.1002/j.1460-2075.1983.tb01534.x

PubMed ID: 6310599

Title: Identification and characterization of human haptoglobin cDNA.

PubMed ID: 6310599

DOI: 10.1073/pnas.80.19.5875

PubMed ID: 6546723

Title: Characterization of human haptoglobin cDNAs coding for alpha 2FS beta and alpha 1S beta variants.

PubMed ID: 6546723

DOI: 10.1016/0014-5793(84)80215-x

PubMed ID: 6330675

Title: Evolution of haptoglobin: comparison of complementary DNA encoding Hp alpha 1S and Hp alpha 2FS.

PubMed ID: 6330675

DOI: 10.1093/nar/12.11.4531

PubMed ID: 4018023

Title: Structure and expression of the human haptoglobin locus.

PubMed ID: 4018023

DOI: 10.1002/j.1460-2075.1985.tb02325.x

PubMed ID: 2987228

Title: Nucleotide sequence of the haptoglobin and haptoglobin-related gene pair. The haptoglobin-related gene contains a retrovirus-like element.

PubMed ID: 2987228

DOI: 10.1016/s0021-9258(18)88836-6

PubMed ID: 1478675

Title: Junctions between genes in the haptoglobin gene cluster of primates.

PubMed ID: 1478675

DOI: 10.1016/s0888-7543(05)80116-8

PubMed ID: 14702039

Title: Complete sequencing and characterization of 21,243 full-length human cDNAs.

PubMed ID: 14702039

DOI: 10.1038/ng1285

PubMed ID: 15616553

Title: The sequence and analysis of duplication-rich human chromosome 16.

PubMed ID: 15616553

DOI: 10.1038/nature03187

PubMed ID: 15489334

Title: The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

PubMed ID: 15489334

DOI: 10.1101/gr.2596504

PubMed ID: 3519135

Title: Expression of cloned human haptoglobin and alpha 1-antitrypsin complementary DNAs in Saccharomyces cerevisiae.

PubMed ID: 3519135

DOI: 10.1089/dna.1986.5.129

PubMed ID: 6310515

Title: Sequence of human haptoglobin cDNA: evidence that the alpha and beta subunits are coded by the same mRNA.

PubMed ID: 6310515

DOI: 10.1093/nar/11.17.5811

PubMed ID: 10493829

Title: Genome duplications and other features in 12 Mb of DNA sequence from human chromosome 16p and 16q.

PubMed ID: 10493829

DOI: 10.1006/geno.1999.5927

PubMed ID: 6325933

Title: Duplication within the haptoglobin Hp2 gene.

PubMed ID: 6325933

DOI: 10.1038/309131a0

PubMed ID: 6997877

Title: Covalent structure of human haptoglobin: a serine protease homolog.

PubMed ID: 6997877

DOI: 10.1073/pnas.77.6.3388

PubMed ID: 7637327

Title: Protein analysis of human maculae in relation to age-related maculopathy.

PubMed ID: 7637327

PubMed ID: 4573324

Title: Studies on the interchain disulfides of human haptoglobins.

PubMed ID: 4573324

DOI: 10.1139/o73-032

PubMed ID: 12754519

Title: Identification and quantification of N-linked glycoproteins using hydrazide chemistry, stable isotope labeling and mass spectrometry.

PubMed ID: 12754519

DOI: 10.1038/nbt827

PubMed ID: 14760718

Title: Screening for N-glycosylated proteins by liquid chromatography mass spectrometry.

PubMed ID: 14760718

DOI: 10.1002/pmic.200300556

PubMed ID: 16335952

Title: Human plasma N-glycoproteome analysis by immunoaffinity subtraction, hydrazide chemistry, and mass spectrometry.

PubMed ID: 16335952

DOI: 10.1021/pr0502065

PubMed ID: 16740002

Title: Identification of N-linked glycoproteins in human saliva by glycoprotein capture and mass spectrometry.

PubMed ID: 16740002

DOI: 10.1021/pr050492k

PubMed ID: 19159218

Title: Glycoproteomics analysis of human liver tissue by combination of multiple enzyme digestion and hydrazide chemistry.

PubMed ID: 19159218

DOI: 10.1021/pr8008012

PubMed ID: 19139490

Title: A strategy for precise and large scale identification of core fucosylated glycoproteins.

PubMed ID: 19139490

DOI: 10.1074/mcp.m800504-mcp200

PubMed ID: 19838169

Title: Enrichment of glycopeptides for glycan structure and attachment site identification.

PubMed ID: 19838169

DOI: 10.1038/nmeth.1392

PubMed ID: 19805376

Title: Identification of human zonulin, a physiological modulator of tight junctions, as prehaptoglobin-2.

PubMed ID: 19805376

DOI: 10.1073/pnas.0906773106

PubMed ID: 19659435

Title: Haptoglobin: basic and clinical aspects.

PubMed ID: 19659435

DOI: 10.1089/ars.2009.2793

PubMed ID: 21269460

Title: Initial characterization of the human central proteome.

PubMed ID: 21269460

DOI: 10.1186/1752-0509-5-17

PubMed ID: 21248165

Title: Zonulin and its regulation of intestinal barrier function: the biological door to inflammation, autoimmunity, and cancer.

PubMed ID: 21248165

DOI: 10.1152/physrev.00003.2008

PubMed ID: 22905912

Title: Resveratrol-induced changes of the human adipocyte secretion profile.

PubMed ID: 22905912

DOI: 10.1021/pr300539b

PubMed ID: 24275569

Title: An enzyme assisted RP-RPLC approach for in-depth analysis of human liver phosphoproteome.

PubMed ID: 24275569

DOI: 10.1016/j.jprot.2013.11.014

PubMed ID: 31142615

Title: The E3 ubiquitin ligase MARCH2 regulates ERGIC3-dependent trafficking of secretory proteins.

PubMed ID: 31142615

DOI: 10.1074/jbc.ra119.007435

PubMed ID: 14999562

Title: A novel I247T missense mutation in the haptoglobin 2 beta-chain decreases the expression of the protein and is associated with ahaptoglobinemia.

PubMed ID: 14999562

DOI: 10.1007/s00439-004-1098-6

Sequence Information:

  • Length: 406
  • Mass: 45205
  • Checksum: A98B56B2B1BE891E
  • Sequence:
  • MSALGAVIAL LLWGQLFAVD SGNDVTDIAD DGCPKPPEIA HGYVEHSVRY QCKNYYKLRT 
    EGDGVYTLND KKQWINKAVG DKLPECEADD GCPKPPEIAH GYVEHSVRYQ CKNYYKLRTE 
    GDGVYTLNNE KQWINKAVGD KLPECEAVCG KPKNPANPVQ RILGGHLDAK GSFPWQAKMV 
    SHHNLTTGAT LINEQWLLTT AKNLFLNHSE NATAKDIAPT LTLYVGKKQL VEIEKVVLHP 
    NYSQVDIGLI KLKQKVSVNE RVMPICLPSK DYAEVGRVGY VSGWGRNANF KFTDHLKYVM 
    LPVADQDQCI RHYEGSTVPE KKTPKSPVGV QPILNEHTFC AGMSKYQEDT CYGDAGSAFA 
    VHDLEEDTWY ATGILSFDKS CAVAEYGVYV KVTSIQDWVQ KTIAEN

Genular Protein ID: 653375965

Symbol: A0A0C4DGL8_HUMAN

Name: N/A

UniProtKB Accession Codes:

Database IDs:

Citations:

PubMed ID: 11237011

Title: Initial sequencing and analysis of the human genome.

PubMed ID: 11237011

DOI: 10.1038/35057062

PubMed ID: 15496913

Title: Finishing the euchromatic sequence of the human genome.

PubMed ID: 15496913

DOI: 10.1038/nature03001

PubMed ID: 15616553

Title: The sequence and analysis of duplication-rich human chromosome 16.

PubMed ID: 15616553

DOI: 10.1038/nature03187

PubMed ID: 21269460

Title: Initial characterization of the human central proteome.

PubMed ID: 21269460

DOI: 10.1186/1752-0509-5-17

PubMed ID: 24275569

Title: An enzyme assisted RP-RPLC approach for in-depth analysis of human liver phosphoproteome.

PubMed ID: 24275569

DOI: 10.1016/j.jprot.2013.11.014

Sequence Information:

  • Length: 347
  • Mass: 38452
  • Checksum: C3A92A17BD401718
  • Sequence:
  • MSALGAVIAL LLWGQLFAVD SGNDVTDIAD DGCPKPPEIA HGYVEHSVRY QCKNYYKLRT 
    EGDGVYTLND KKQWINKAVG DKLPECEAVC GKPKNPANPV QRILGGHLDA KGSFPWQAKM 
    VSHHNLTTGA TLINEQWLLT TAKNLFLNHS ENATAKDIAP TLTLYVGKKQ LVEIEKVVLH 
    PNYSQVDIGL IKLKQKVSVN ERVMPICLPS KDYAEVGRVG YVSGWGRNAN FKFTDHLKYV 
    MLPVADQDQC IRHYEGSTVP EKKTPKSPVG VQPILNEHTF CAGMSKYQED TCYGDAGSAF 
    AVHDLEEDTW YATGILSFDK SCAVAEYGVY VKVTSIQDWV QKTIAEN

Genular Protein ID: 1625413079

Symbol: Q6PEJ8_HUMAN

Name: N/A

UniProtKB Accession Codes:

Database IDs:

Citations:

PubMed ID: 15489334

Title: The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).

PubMed ID: 15489334

DOI: 10.1101/gr.2596504

Sequence Information:

  • Length: 228
  • Mass: 25458
  • Checksum: 82D0E68C4584E8E9
  • Sequence:
  • MVSHHNLTTG ATLINEQWLL TTAKNLFLNH SENATAKDIA PTLTLYVGKK QLVEIEKVVL 
    HPNYSQVDIG LIKLKQKVSV NERVMPICLP SKDYAEVGRV GYVSGWGRNA NFKFTDHLKY 
    VMLPVADQDQ CIRHYEGSTV PEKKTPKSPV GVQPILNEHT FCAGMSKYQE DTCYGDAGSA 
    FAVHDLEEDT WYATGILSFD KSCAVAEYGV YVKVTSIQDW VQKTIAEN