| HGNC Family | Hemoglobin subunits (HB) |
| Name | hemoglobin, alpha 2 |
| Description | The human alpha globin gene cluster located on chromosome 16 spans about 30 kb and includes seven loci: 5'- zeta - pseudozeta - mu - pseudoalpha-1 - alpha-2 - alpha-1 - theta - 3'. The alpha-2 (HBA2) and alpha-1 (HBA1) coding sequences are identical. These genes differ slightly over the 5' untranslated regions and the introns, but they differ significantly over the 3' untranslated regions. Two alpha chains plus two beta chains constitute HbA, which in normal adult life comprises about 97% of the total hemoglobin; alpha chains combine with delta chains to constitute HbA-2, which with HbF (fetal hemoglobin) makes up the remaining 3% of adult hemoglobin. Alpha thalassemias result from deletions of each of the alpha genes as well as deletions of both HBA2 and HBA1; some nondeletion alpha thalassemias have also been reported. [provided by RefSeq, Jul 2008] |
| Summary |
{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Hemoglobin α, which is encoded by both HBA1 and HBA2, is best known for its role in oxygen transport within erythrocytes; however, recent studies have uncovered important functions for this protein in nonerythroid cells. In particular, endothelial cell–expressed hemoglobin α localizes to the myoendothelial junction where it plays a critical role in modulating nitric oxide (NO) signaling and vascular reactivity. In its ferric [Fe(3+)] state, hemoglobin α permits NO-mediated relaxation of vascular smooth muscle cells, whereas reduction of its heme iron to the ferrous [Fe(2+)] state by cytochrome b5 reductase 3 shuts off NO signaling. Given that HBA2 encodes one of the α globin chains, its expression in endothelial cells contributes to this dynamic regulation of local NO bioactivity, thereby influencing blood pressure and vascular tone."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Additional evidence from investigations in nonerythroid tissues supports a more general role for hemoglobin α in cellular protection against oxidative stress. In hepatocytes and certain cancer cells, for example, expression of hemoglobin subunits is upregulated by reactive oxygen species, and the resultant protein appears to act as an intracellular antioxidant that buffers oxidative damage."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "2"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Thus, beyond its well‐characterized role in oxygen carriage, HBA2 contributes to the fine tuning of vascular NO signaling and may also help protect against oxidative injury in diverse cell types.\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Adam C Straub, Alexander W Lohman, Marie Billaud, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Endothelial cell expression of haemoglobin α regulates nitric oxide signalling."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Nature (2012)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1038/nature11626"}], "href": "https://doi.org/10.1038/nature11626"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23123858"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23123858"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Wensheng Liu, Susan S Baker, Robert D Baker, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Upregulation of hemoglobin expression by oxidative stress in hepatocytes and its implication in nonalcoholic steatohepatitis."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "PLoS One (2011)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1371/journal.pone.0024363"}], "href": "https://doi.org/10.1371/journal.pone.0024363"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "21931690"}], "href": "https://pubmed.ncbi.nlm.nih.gov/21931690"}]}, {"type": "r", "ref": 3, "children": [{"type": "t", "text": "Xiaolei Li, Zhiqiang Wu, Yao Wang, et al. "}, {"type": "b", "children": [{"type": "t", "text": "Characterization of adult α- and β-globin elevated by hydrogen peroxide in cervical cancer cells that play a cytoprotective role against oxidative insults."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "PLoS One (2013)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1371/journal.pone.0054342"}], "href": "https://doi.org/10.1371/journal.pone.0054342"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "23349856"}], "href": "https://pubmed.ncbi.nlm.nih.gov/23349856"}]}]}]}
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| Synonyms | HBA-T2 |
| NCBI Gene ID | 3040 |
| API | |
| Download Associations | |
| Predicted Functions |
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| Co-expressed Genes |
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| Expression in Tissues and Cell Lines |
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HBA2 has 6,233 functional associations with biological entities spanning 8 categories (molecular profile, organism, functional term, phrase or reference, disease, phenotype or trait, chemical, cell line, cell type or tissue, gene, protein or microRNA, sequence feature) extracted from 83 datasets.
Click the + buttons to view associations for HBA2 from the datasets below.
If available, associations are ranked by standardized value
| Dataset | Summary | |
|---|---|---|
| Allen Brain Atlas Adult Human Brain Tissue Gene Expression Profiles | tissues with high or low expression of HBA2 gene relative to other tissues from the Allen Brain Atlas Adult Human Brain Tissue Gene Expression Profiles dataset. | |
| Allen Brain Atlas Developing Human Brain Tissue Gene Expression Profiles by RNA-seq | tissue samples with high or low expression of HBA2 gene relative to other tissue samples from the Allen Brain Atlas Developing Human Brain Tissue Gene Expression Profiles by RNA-seq dataset. | |
| Allen Brain Atlas Prenatal Human Brain Tissue Gene Expression Profiles | tissues with high or low expression of HBA2 gene relative to other tissues from the Allen Brain Atlas Prenatal Human Brain Tissue Gene Expression Profiles dataset. | |
| Biocarta Pathways | pathways involving HBA2 protein from the Biocarta Pathways dataset. | |
| CCLE Cell Line Gene CNV Profiles | cell lines with high or low copy number of HBA2 gene relative to other cell lines from the CCLE Cell Line Gene CNV Profiles dataset. | |
| CellMarker Gene-Cell Type Associations | cell types associated with HBA2 gene from the CellMarker Gene-Cell Type Associations dataset. | |
| ChEA Transcription Factor Binding Site Profiles | transcription factor binding site profiles with transcription factor binding evidence at the promoter of HBA2 gene from the CHEA Transcription Factor Binding Site Profiles dataset. | |
| ChEA Transcription Factor Targets | transcription factors binding the promoter of HBA2 gene in low- or high-throughput transcription factor functional studies from the CHEA Transcription Factor Targets dataset. | |
| ChEA Transcription Factor Targets 2022 | transcription factors binding the promoter of HBA2 gene in low- or high-throughput transcription factor functional studies from the CHEA Transcription Factor Targets 2022 dataset. | |
| ClinVar Gene-Phenotype Associations | phenotypes associated with HBA2 gene from the curated ClinVar Gene-Phenotype Associations dataset. | |
| COMPARTMENTS Curated Protein Localization Evidence Scores | cellular components containing HBA2 protein from the COMPARTMENTS Curated Protein Localization Evidence Scores dataset. | |
| COMPARTMENTS Curated Protein Localization Evidence Scores 2025 | cellular components containing HBA2 protein from the COMPARTMENTS Curated Protein Localization Evidence Scores 2025 dataset. | |
| COMPARTMENTS Text-mining Protein Localization Evidence Scores | cellular components co-occuring with HBA2 protein in abstracts of biomedical publications from the COMPARTMENTS Text-mining Protein Localization Evidence Scores dataset. | |
| COMPARTMENTS Text-mining Protein Localization Evidence Scores 2025 | cellular components co-occuring with HBA2 protein in abstracts of biomedical publications from the COMPARTMENTS Text-mining Protein Localization Evidence Scores 2025 dataset. | |
| COSMIC Cell Line Gene CNV Profiles | cell lines with high or low copy number of HBA2 gene relative to other cell lines from the COSMIC Cell Line Gene CNV Profiles dataset. | |
| COSMIC Cell Line Gene Mutation Profiles | cell lines with HBA2 gene mutations from the COSMIC Cell Line Gene Mutation Profiles dataset. | |
| CTD Gene-Chemical Interactions | chemicals interacting with HBA2 gene/protein from the curated CTD Gene-Chemical Interactions dataset. | |
| CTD Gene-Disease Associations | diseases associated with HBA2 gene/protein from the curated CTD Gene-Disease Associations dataset. | |
| DISEASES Curated Gene-Disease Association Evidence Scores | diseases involving HBA2 gene from the DISEASES Curated Gene-Disease Assocation Evidence Scores dataset. | |
| DISEASES Curated Gene-Disease Association Evidence Scores 2025 | diseases involving HBA2 gene from the DISEASES Curated Gene-Disease Association Evidence Scores 2025 dataset. | |
| DISEASES Experimental Gene-Disease Association Evidence Scores 2025 | diseases associated with HBA2 gene in GWAS datasets from the DISEASES Experimental Gene-Disease Assocation Evidence Scores 2025 dataset. | |
| DISEASES Text-mining Gene-Disease Association Evidence Scores | diseases co-occuring with HBA2 gene in abstracts of biomedical publications from the DISEASES Text-mining Gene-Disease Assocation Evidence Scores dataset. | |
| DISEASES Text-mining Gene-Disease Association Evidence Scores 2025 | diseases co-occuring with HBA2 gene in abstracts of biomedical publications from the DISEASES Text-mining Gene-Disease Assocation Evidence Scores 2025 dataset. | |
| DisGeNET Gene-Disease Associations | diseases associated with HBA2 gene in GWAS and other genetic association datasets from the DisGeNET Gene-Disease Associations dataset. | |
| DisGeNET Gene-Phenotype Associations | phenotypes associated with HBA2 gene in GWAS and other genetic association datasets from the DisGeNET Gene-Phenoptype Associations dataset. | |
| ENCODE Histone Modification Site Profiles | histone modification site profiles with high histone modification abundance at HBA2 gene from the ENCODE Histone Modification Site Profiles dataset. | |
| ENCODE Transcription Factor Binding Site Profiles | transcription factor binding site profiles with transcription factor binding evidence at the promoter of HBA2 gene from the ENCODE Transcription Factor Binding Site Profiles dataset. | |
| ENCODE Transcription Factor Targets | transcription factors binding the promoter of HBA2 gene in ChIP-seq datasets from the ENCODE Transcription Factor Targets dataset. | |
| GAD Gene-Disease Associations | diseases associated with HBA2 gene in GWAS and other genetic association datasets from the GAD Gene-Disease Associations dataset. | |
| GAD High Level Gene-Disease Associations | diseases associated with HBA2 gene in GWAS and other genetic association datasets from the GAD High Level Gene-Disease Associations dataset. | |
| GDSC Cell Line Gene Expression Profiles | cell lines with high or low expression of HBA2 gene relative to other cell lines from the GDSC Cell Line Gene Expression Profiles dataset. | |
| GeneRIF Biological Term Annotations | biological terms co-occuring with HBA2 gene in literature-supported statements describing functions of genes from the GeneRIF Biological Term Annotations dataset. | |
| GeneSigDB Published Gene Signatures | PubMedIDs of publications reporting gene signatures containing HBA2 from the GeneSigDB Published Gene Signatures dataset. | |
| GEO Signatures of Differentially Expressed Genes for Diseases | disease perturbations changing expression of HBA2 gene from the GEO Signatures of Differentially Expressed Genes for Diseases dataset. | |
| GEO Signatures of Differentially Expressed Genes for Gene Perturbations | gene perturbations changing expression of HBA2 gene from the GEO Signatures of Differentially Expressed Genes for Gene Perturbations dataset. | |
| GEO Signatures of Differentially Expressed Genes for Small Molecules | small molecule perturbations changing expression of HBA2 gene from the GEO Signatures of Differentially Expressed Genes for Small Molecules dataset. | |
| GEO Signatures of Differentially Expressed Genes for Transcription Factor Perturbations | transcription factor perturbations changing expression of HBA2 gene from the GEO Signatures of Differentially Expressed Genes for Transcription Factor Perturbations dataset. | |
| GEO Signatures of Differentially Expressed Genes for Viral Infections | virus perturbations changing expression of HBA2 gene from the GEO Signatures of Differentially Expressed Genes for Viral Infections dataset. | |
| GlyGen Glycosylated Proteins | ligands (chemical) binding HBA2 protein from the GlyGen Glycosylated Proteins dataset. | |
| GTEx eQTL 2025 | SNPs regulating expression of HBA2 gene from the GTEx eQTL 2025 dataset. | |
| GTEx Tissue Gene Expression Profiles | tissues with high or low expression of HBA2 gene relative to other tissues from the GTEx Tissue Gene Expression Profiles dataset. | |
| GTEx Tissue Gene Expression Profiles 2023 | tissues with high or low expression of HBA2 gene relative to other tissues from the GTEx Tissue Gene Expression Profiles 2023 dataset. | |
| GTEx Tissue Sample Gene Expression Profiles | tissue samples with high or low expression of HBA2 gene relative to other tissue samples from the GTEx Tissue Sample Gene Expression Profiles dataset. | |
| GTEx Tissue-Specific Aging Signatures | tissue samples with high or low expression of HBA2 gene relative to other tissue samples from the GTEx Tissue-Specific Aging Signatures dataset. | |
| HPA Cell Line Gene Expression Profiles | cell lines with high or low expression of HBA2 gene relative to other cell lines from the HPA Cell Line Gene Expression Profiles dataset. | |
| HPA Tissue Gene Expression Profiles | tissues with high or low expression of HBA2 gene relative to other tissues from the HPA Tissue Gene Expression Profiles dataset. | |
| HPA Tissue Protein Expression Profiles | tissues with high or low expression of HBA2 protein relative to other tissues from the HPA Tissue Protein Expression Profiles dataset. | |
| HPA Tissue Sample Gene Expression Profiles | tissue samples with high or low expression of HBA2 gene relative to other tissue samples from the HPA Tissue Sample Gene Expression Profiles dataset. | |
| HPM Cell Type and Tissue Protein Expression Profiles | cell types and tissues with high or low expression of HBA2 protein relative to other cell types and tissues from the HPM Cell Type and Tissue Protein Expression Profiles dataset. | |
| HPO Gene-Disease Associations | phenotypes associated with HBA2 gene by mapping known disease genes to disease phenotypes from the HPO Gene-Disease Associations dataset. | |
| Hub Proteins Protein-Protein Interactions | interacting hub proteins for HBA2 from the curated Hub Proteins Protein-Protein Interactions dataset. | |
| HuBMAP ASCT+B Annotations | cell types associated with HBA2 gene from the HuBMAP ASCT+B dataset. | |
| HuBMAP ASCT+B Augmented with RNA-seq Coexpression | cell types associated with HBA2 gene from the HuBMAP ASCT+B Augmented with RNA-seq Coexpression dataset. | |
| HuBMAP Azimuth Cell Type Annotations | cell types associated with HBA2 gene from the HuBMAP Azimuth Cell Type Annotations dataset. | |
| HuGE Navigator Gene-Phenotype Associations | phenotypes associated with HBA2 gene by text-mining GWAS publications from the HuGE Navigator Gene-Phenotype Associations dataset. | |
| JASPAR Predicted Transcription Factor Targets | transcription factors regulating expression of HBA2 gene predicted using known transcription factor binding site motifs from the JASPAR Predicted Transcription Factor Targets dataset. | |
| Klijn et al., Nat. Biotechnol., 2015 Cell Line Gene CNV Profiles | cell lines with high or low copy number of HBA2 gene relative to other cell lines from the Klijn et al., Nat. Biotechnol., 2015 Cell Line Gene CNV Profiles dataset. | |
| Klijn et al., Nat. Biotechnol., 2015 Cell Line Gene Mutation Profiles | cell lines with HBA2 gene mutations from the Klijn et al., Nat. Biotechnol., 2015 Cell Line Gene Mutation Profiles dataset. | |
| KnockTF Gene Expression Profiles with Transcription Factor Perturbations | transcription factor perturbations changing expression of HBA2 gene from the KnockTF Gene Expression Profiles with Transcription Factor Perturbations dataset. | |
| MGI Mouse Phenotype Associations 2023 | phenotypes of transgenic mice caused by HBA2 gene mutations from the MGI Mouse Phenotype Associations 2023 dataset. | |
| MotifMap Predicted Transcription Factor Targets | transcription factors regulating expression of HBA2 gene predicted using known transcription factor binding site motifs from the MotifMap Predicted Transcription Factor Targets dataset. | |
| MSigDB Signatures of Differentially Expressed Genes for Cancer Gene Perturbations | gene perturbations changing expression of HBA2 gene from the MSigDB Signatures of Differentially Expressed Genes for Cancer Gene Perturbations dataset. | |
| NIBR DRUG-seq U2OS MoA Box Gene Expression Profiles | drug perturbations changing expression of HBA2 gene from the NIBR DRUG-seq U2OS MoA Box dataset. | |
| OMIM Gene-Disease Associations | phenotypes associated with HBA2 gene from the curated OMIM Gene-Disease Associations dataset. | |
| Pathway Commons Protein-Protein Interactions | interacting proteins for HBA2 from the Pathway Commons Protein-Protein Interactions dataset. | |
| PerturbAtlas Signatures of Differentially Expressed Genes for Gene Perturbations | gene perturbations changing expression of HBA2 gene from the PerturbAtlas Signatures of Differentially Expressed Genes for Gene Perturbations dataset. | |
| PFOCR Pathway Figure Associations 2023 | pathways involving HBA2 protein from the PFOCR Pathway Figure Associations 2023 dataset. | |
| PFOCR Pathway Figure Associations 2024 | pathways involving HBA2 protein from the Wikipathways PFOCR 2024 dataset. | |
| Roadmap Epigenomics Cell and Tissue Gene Expression Profiles | cell types and tissues with high or low expression of HBA2 gene relative to other cell types and tissues from the Roadmap Epigenomics Cell and Tissue Gene Expression Profiles dataset. | |
| Roadmap Epigenomics Histone Modification Site Profiles | histone modification site profiles with high histone modification abundance at HBA2 gene from the Roadmap Epigenomics Histone Modification Site Profiles dataset. | |
| RummaGEO Drug Perturbation Signatures | drug perturbations changing expression of HBA2 gene from the RummaGEO Drug Perturbation Signatures dataset. | |
| RummaGEO Gene Perturbation Signatures | gene perturbations changing expression of HBA2 gene from the RummaGEO Gene Perturbation Signatures dataset. | |
| Tabula Sapiens Gene-Cell Associations | cell types with high or low expression of HBA2 gene relative to other cell types from the Tabula Sapiens Gene-Cell Associations dataset. | |
| TargetScan Predicted Conserved microRNA Targets | microRNAs regulating expression of HBA2 gene predicted using conserved miRNA seed sequences from the TargetScan Predicted Conserved microRNA Targets dataset. | |
| TargetScan Predicted Nonconserved microRNA Targets | microRNAs regulating expression of HBA2 gene predicted using nonconserved miRNA seed sequences from the TargetScan Predicted Nonconserved microRNA Targets dataset. | |
| TCGA Signatures of Differentially Expressed Genes for Tumors | tissue samples with high or low expression of HBA2 gene relative to other tissue samples from the TCGA Signatures of Differentially Expressed Genes for Tumors dataset. | |
| TISSUES Curated Tissue Protein Expression Evidence Scores | tissues with high expression of HBA2 protein from the TISSUES Curated Tissue Protein Expression Evidence Scores dataset. | |
| TISSUES Curated Tissue Protein Expression Evidence Scores 2025 | tissues with high expression of HBA2 protein from the TISSUES Curated Tissue Protein Expression Evidence Scores 2025 dataset. | |
| TISSUES Experimental Tissue Protein Expression Evidence Scores | tissues with high expression of HBA2 protein in proteomics datasets from the TISSUES Experimental Tissue Protein Expression Evidence Scores dataset. | |
| TISSUES Experimental Tissue Protein Expression Evidence Scores 2025 | tissues with high expression of HBA2 protein in proteomics datasets from the TISSUES Experimental Tissue Protein Expression Evidence Scores 2025 dataset. | |
| TISSUES Text-mining Tissue Protein Expression Evidence Scores | tissues co-occuring with HBA2 protein in abstracts of biomedical publications from the TISSUES Text-mining Tissue Protein Expression Evidence Scores dataset. | |
| TISSUES Text-mining Tissue Protein Expression Evidence Scores 2025 | tissues co-occuring with HBA2 protein in abstracts of biomedical publications from the TISSUES Text-mining Tissue Protein Expression Evidence Scores 2025 dataset. | |
| WikiPathways Pathways 2014 | pathways involving HBA2 protein from the Wikipathways Pathways 2014 dataset. | |
