HLA-DQA1: Polycystic Ovarian Syndrome Database

Gene Information

Gene Symbol

HLA-DQA1

Aliases

CELIAC1, DQ-A1, DQA1, HLA-DQA

Entrez Gene ID

3117

Gene Name

Major histocompatibility complex, class II, DQ alpha 1

Chromosomal Location

6p21.32

HGNC ID

HGNC:4942

Summary

HLA-DQA1 belongs to the HLA class II alpha chain paralogues. The 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). The alpha chain is approximately 33-35 kDa. It is encoded by 5 exons; exon 1 encodes the leader peptide, exons 2 and 3 encode the two extracellular domains, and 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 four different molecules. Typing for these polymorphisms is routinely done for bone marrow transplantation. [provided by RefSeq, Jul 2008]

RefSeq DNA

NG_032876.1

RefSeq mRNA

NM_002122.4, NM_002122.5

e!Ensembl

Gene	ENSG00000196735, ENSG00000206305, ENSG00000237541, ENSG00000225103, ENSG00000225890, ENSG00000228284, ENSG00000206301, ENSG00000233192, ENSG00000231823, ENSG00000232062, ENSG00000231526, ENSG00000257473, ENSG00000236418, ENSG00000223793
Transcript	ENST00000422863, ENST00000343139, ENST00000395363, ENST00000496318, ENST00000374949, ENST00000482745, ENST00000383251, ENST00000399675, ENST00000399678, ENST00000374940, ENST00000446482, ENST00000448163, ENST00000443320, ENST00000451947, ENST00000416403, ENST00000442680, ENST00000468299, ENST00000445944, ENST00000456258, ENST00000450614, ENST00000441297, ENST00000420385, ENST00000484643, ENST00000241802, ENST00000547960, ENST00000449560, ENST00000546801, ENST00000453672, ENST00000418023, ENST00000444296, ENST00000415898, ENST00000443184, ENST00000552745, ENST00000414549, ENST00000453504, ENST00000457246, ENST00000442315, ENST00000450960, ENST00000461508, ENST00000640446, ENST00000447735, ENST00000551533
Protein	ENSP00000405797, ENSP00000339398, ENSP00000378767, ENSP00000437302, ENSP00000364087, ENSP00000436546, ENSP00000372738, ENSP00000382583, ENSP00000382586, ENSP00000364076, ENSP00000390725, ENSP00000413816, ENSP00000401151, ENSP00000412055, ENSP00000409127, ENSP00000401436, ENSP00000431277, ENSP00000413815, ENSP00000392580, ENSP00000399068, ENSP00000404172, ENSP00000414360, ENSP00000436724, ENSP00000241802, ENSP00000446860, ENSP00000401098, ENSP00000447668, ENSP00000387768, ENSP00000387892, ENSP00000413237, ENSP00000400695, ENSP00000405833, ENSP00000447257, ENSP00000394388, ENSP00000401760, ENSP00000405476, ENSP00000416641, ENSP00000415001, ENSP00000436314, ENSP00000491360, ENSP00000393431, ENSP00000448003

Gene Ontology (GO)

Show/Hide all(8 )

GO ID	Ontology	Function	Evidence	Reference
GO:0006955	Biological process	Immune response	NAS	3584986, 6415485
GO:0005887	Cellular component	Integral component of plasma membrane	NAS	3584986, 6415485
GO:0016020	Cellular component	Membrane	HDA	19946888
GO:0042613	Cellular component	MHC class II protein complex	ISS	20356827
GO:0005515	Molecular function	Protein binding	IPI	14769912, 17629515, 29997244
GO:0032395	Molecular function	MHC class II receptor activity	NAS	3584986, 6415485
GO:0032395	Molecular function	MHC class II receptor activity	TAS	2300572
GO:0042605	Molecular function	Peptide antigen binding	ISS	20356827

Protein Information

Protein Name

HLA class II histocompatibility antigen, DQ alpha 1 chain, DC-1 alpha chain, DC-alpha, HLA-DCA, MHC HLA-DQ alpha, MHC class II DQ alpha chain, MHC class II DQA1, MHC class II HLA-DQ-alpha-1, MHC class II antigen DQA1, truncated MHC class II antigen

Function

Binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for recognition by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mostly by degradation of proteins that access the endocytic route, where they are processed by lysosomal proteases and other hydrolases. Exogenous antigens that have been endocytosed by the APC are thus readily available for presentation via MHC II molecules, and for this reason this antigen presentation pathway is usually referred to as exogenous. As membrane proteins on their way to degradation in lysosomes as part of their normal turn-over are also contained in the endosomal/lysosomal compartments, exogenous antigens must compete with those derived from endogenous components. Autophagy is also a source of endogenous peptides, autophagosomes constitutively fuse with MHC class II loading compartments. In addition to APCs, other cells of the gastrointestinal tract, such as epithelial cells, express MHC class II molecules and CD74 and act as APCs, which is an unusual trait of the GI tract. To produce a MHC class II molecule that presents an antigen, three MHC class II molecules (heterodimers of an alpha and a beta chain) associate with a CD74 trimer in the ER to form a heterononamer. Soon after the entry of this complex into the endosomal/lysosomal system where antigen processing occurs, CD74 undergoes a sequential degradation by various proteases, including CTSS and CTSL, leaving a small fragment termed CLIP (class-II-associated invariant chain peptide). The removal of CLIP is facilitated by HLA-DM via direct binding to the alpha-beta-CLIP complex so that CLIP is released. HLA-DM stabilizes MHC class II molecules until primary high affinity antigenic peptides are bound. The MHC II molecule bound to a peptide is then transported to the cell membrane surface. In B-cells, the interaction between HLA-DM and MHC class II molecules is regulated by HLA-DO. Primary dendritic cells (DCs) also to express HLA-DO. Lysosomal microenvironment has been implicated in the regulation of antigen loading into MHC II molecules, increased acidification produces increased proteolysis and efficient peptide loading

Refseq Proteins

NP_002113.2

UniProt

P01909

PDB

1JK8, 1NBN, 1S9V, 1UVQ, 2NNA, 4GG6, 4OZF, 4OZG, 4OZH, 4OZI, 5KSA, 5KSB, 5KSU, 5KSV, 6MFF, 6MFG, 3PL6, 4D8P, 5KS9

HLA-DQA1

Increased risk for polycystic ovary syndrome associated with human leukocyte antigen DQA1*0501.