Major histocompatibility complex, class II, DQ alpha 1

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Major histocompatibility complex, class II, DQ alpha 1
1UVQ.png
Structure of HLA-DQA1 (cyan) complexed with HLA-DQB1 (green) and HCRT (magenta) based on PDB 1uvq.
Available structures
PDB Ortholog search: PDBe, RCSB
Identifiers
Symbols HLA-DQA1 ; CD; CELIAC1; DQ-A1; GSE; HLA-DQA
External IDs OMIM146880 MGI95895 HomoloGene123820 GeneCards: HLA-DQA1 Gene
RNA expression pattern
PBB GE HLA-DQA1 212671 s at tn.png
More reference expression data
Orthologs
Species Human Mouse
Entrez 3117 14960
Ensembl ENSG00000196735 ENSMUSG00000036594
UniProt P01909 P14434
RefSeq (mRNA) NM_002122 NM_010378
RefSeq (protein) NP_002113 NP_034508
Location (UCSC) Chr 6:
32.6 – 32.61 Mb
Chr 17:
34.28 – 34.29 Mb
PubMed search [1] [2]

Major histocompatibility complex, class II, DQ alpha 1, also known as HLA-DQA1, is a human gene present on short arm of chromosome 6 (6p21.3) and also denotes the genetic locus which contains this gene.[1] The protein encoded by this gene is one of two proteins that are required to form the DQ heterodimer, a cell surface receptor essential to the function of the immune system.

Function[edit]

HLA-DQA1 belongs to the HLA class II alpha chain paralogues. This class II molecule is a heterodimer consisting of an alpha (DQA) and a beta chain (DQB), both anchored in the membrane. It plays a central role in the immune system by presenting peptides derived from extracellular proteins. Class II molecules are expressed in antigen-presenting cells (APC: B lymphocytes, dendritic cells, macrophages).[1]

Gene structure and polymorphisms[edit]

The alpha chain contains 5 exons. Exon one encodes the leader peptide, exons 2 and 3 encode the two extracellular protein domains, exon 4 encodes the transmembrane domain and the cytoplasmic tail. Within the DQ molecule both the alpha chain and the beta chain contain the polymorphisms specifying the peptide binding specificities, resulting in up to 4 different molecules. Typing for these polymorphisms is routinely done for bone marrow transplantation.[1][2]

Alleles[edit]

DQ1[edit]

There are four commonly encountered DQA1 alleles: DQA1*0101, *0102, *0103, *0104. These alleles are always found in haplotypes with HLA-DQB1*05 (DQ5) and HLA-DQB1*06 (DQ6). DQ1 is a serotype, rare among serotypes for human class II antigens, in that the antibodies to DQ1 react to the alpha chain of HLA DQ, these DQA1 allele gene products.

HLA-DQA1 alleles
DQA1 linked DQB1 allele
DQ1 *0101 *0501 *0301
*0102 *0502 *0504 *0602 *0604 *0605 *0609
*0103 *0501 *0502 *0601 *0602 *0603
*0104 *0501 *0503 *0602
*0105 rare
*0106 rare
See haplotype table in HLA-DQ. Unbolded are rare haplotypes
Link to haplotypes can be followed by DQB1 alleles

Other[edit]

The other DQA1 alleles have no defined serotype. There are 5 groups, DQA1*02, *03, *04, *05, *06. DQA1 within these groups are either invariant or produce the same α-chain subunit. DQA1*02 and DQA1*06 contain only one allele. DQA1*03 has three alleles which each produce nearly identical α3. For DQA1*05, the DQA1*0501 and DQA1*0505 produce identical α5. Other DQA1*05 exist that produce variant α5var, but these are rare.

HLA-DQA1 alleles
DQA1 linked DQB1 allele
*0201 *0202 *0303
*0301 *0202 *0302
*0302
*0303 *0301 *0602
*0401 *0303 *0401 *0402
*0501 *0201
*0505 *0301
*0601 *0301
See haplotype table in HLA-DQ. Unbolded are rare haplotypes
Link to haplotypes can be followed by DQB1 alleles

See also[edit]

References[edit]

  1. ^ a b c "Entrez Gene: HLA-DQA1 major histocompatibility complex, class II, DQ alpha 1". 
  2. ^ Lau M, Terasaki PI, Park MS (1994). "International Cell Exchange, 1994". Clin Transpl: 467–88. PMID 7547576. 

Further reading[edit]