HLA-A

Also known as HLAA, Aw-33, Aw-74, major histocompatibility complex, class I, A, HLA-A11, HLA-A33, HLA-DQB1, HLA-DRB1

HLA-A is a group of human leukocyte antigens (HLA) that are encoded by the HLA-A locus, which is located at human chromosome 6p21.3. HLA is a major histocompatibility complex (MHC) antigen specific to humans. HLA-A is one of three major types of human MHC class I transmembrane proteins. The others are HLA-B and HLA-C. The protein is a heterodimer, and is composed of a heavy α chain and smaller β chain. The α chain is encoded by a variant HLA-A gene, and the β chain (β2-microglobulin) is an invariant β2 microglobulin molecule. The β2 microglobulin protein is encoded by the B2M gene, which is lo

Key facts

Heteropolypeptide.heteropolymer: MHC class I, A
Heteropolypeptide.polymer_type: heterodimer
Heteropolypeptide.protein_type: Transmembrane protein
Heteropolypeptide.function: Peptide presentation for immune recognition
Heteropolypeptide.image: Illustration_HLA-A.png
Heteropolypeptide.image_source: Illustration of HLA-A
Heteropolypeptide.SubunitCount: 2
Heteropolypeptide.subunit1: α
Heteropolypeptide.gene1: HLA-A
Heteropolypeptide.locus1: Chromosome 6p21.3
Heteropolypeptide.subunit2: β2M
Heteropolypeptide.gene2: B2M
Heteropolypeptide.locus2: Chromosome 15q22

via Wikipedia infobox

Gene data

HLA-A

Name: major histocompatibility complex, class I, A
Type: protein-coding
Position: 29,941,260–29,949,572 (+)
Aliases: HLAA
Ensembl: ENSG00000227715
RefSeq RNA: NM_001242758.1, NM_002116.8, XM_041680767.1, XM_041680768.2
RefSeq protein: NP_001229687.1, NP_002107.3, XP_041536701.1, XP_041536702.1

HLA-A belongs to the HLA class I heavy chain paralogues. This class I molecule is a heterodimer consisting of a heavy chain and a light chain (beta-2 microglobulin). The heavy chain is anchored in the membrane. Class I molecules play a central role in the immune system by presenting peptides derived from the endoplasmic reticulum lumen so that they can be recognized by cytotoxic T cells. They are expressed in nearly all cells. The heavy chain is approximately 45 kDa and its gene contains 8 exons. Exon 1 encodes the leader peptide, exons 2 and 3 encode the alpha1 and alpha2 domains, which both bind the peptide, exon 4 encodes the alpha3 domain, exon 5 encodes the transmembrane region, and exons 6 and 7 encode the cytoplasmic tail. Polymorphisms within exon 2 and exon 3 are responsible for the peptide binding specificity of each class one molecule. Typing for these polymorphisms is routinely done for bone marrow and kidney transplantation. More than 6000 HLA-A alleles have been described. The HLA system plays an important role in the occurrence and outcome of infectious diseases, including those caused by the malaria parasite, the human immunodeficiency virus (HIV), and the severe acute respiratory syndrome coronavirus (SARS-CoV). The structural spike and the nucleocapsid proteins of the novel coronavirus SARS-CoV-2, which causes coronavirus disease 2019 (COVID-19), are reported to contain multiple Class I epitopes with predicted HLA restrictions. Individual HLA genetic variation may help explain different immune responses to a virus across a population.[provided by RefSeq, Aug 2020].

Gene Ontology

Biological process

T cell mediated cytotoxicity positive regulation of T cell mediated cytotoxicity positive regulation of T cell mediated cytotoxicity T cell mediated cytotoxicity directed against tumor cell target antigen processing and presentation of endogenous peptide antigen via MHC class Ib antigen processing and presentation of exogenous peptide antigen via MHC class Ib antigen processing and presentation of endogenous peptide antigen via MHC class I via ER pathway, TAP-dependent antigen processing and presentation of endogenous peptide antigen via MHC class I via ER pathway, TAP-independent

Molecular function

RNA binding signaling receptor binding signaling receptor binding protein binding beta-2-microglobulin binding beta-2-microglobulin binding beta-2-microglobulin binding beta-2-microglobulin binding

Cellular component

Golgi membrane Golgi membrane extracellular region endoplasmic reticulum endoplasmic reticulum membrane endoplasmic reticulum membrane Golgi apparatus Golgi medial cisterna

Pathways

Endocytosis - Homo sapiens (human)Phagosome - Homo sapiens (human)Cellular senescence - Homo sapiens (human)Cell adhesion molecules - Homo sapiens (human)Antigen processing and presentation - Homo sapiens (human)Natural killer cell mediated cytotoxicity - Homo sapiens (human)Type I diabetes mellitus - Homo sapiens (human)Human cytomegalovirus infection - Homo sapiens (human)Human papillomavirus infection - Homo sapiens (human)Human T-cell leukemia virus 1 infection - Homo sapiens (human)

via MyGene.info

Wikidata facts

Image: HLA-A*02 protein structure.jpg

Show 6 more facts

HomoloGene ID: 128352
exact match: identifiers.org/ncbigene/3105
genomic start: 29909037
genomic end: 29913661
cytogenetic location: 6p22.1
Commons category: HLA-A

Sources (5)

via Wikidata · CC0

~17 min read

Article

11 sections

Contents

''HLA-A'' gene
Alleles
Protein
Function
Natural function
Other activities
Role in disease
{{anchor|HIV/AIDS}} HIV/AIDS
Summary
References
External links

MHC Class I molecules such as HLA-A participate in a process that presents short polypeptides to the immune system. These polypeptides are typically 7–11 amino acids in length and originate from proteins being expressed by the cell. There are two classes of polypeptide that can be presented by an HLA protein: those that are supposed to be expressed by the cell (self) and those of foreign derivation (non-self). Under normal conditions cytotoxic T cells, which normally patrol the body in the blood, "read" the peptide presented by the complex. T cells, if functioning properly, only bind to non-self peptides. If binding occurs, a series of events is initiated culminating in cell death via apoptosis. In this manner, the human body eliminates any cells infected by a virus or expressing proteins they shouldn't be (e.g. cancerous cells).