Target Information
Target General Information | Top | |||||
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Target ID |
T50768
(Former ID: TTDI02055)
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Target Name |
HLA class II antigen DQ-2 alpha (HLA-DQA1)
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Synonyms |
MHC class II DQA1; HLADQA1; HLADCA; HLA-DQA1; HLA class II histocompatibility antigen, DQ alpha 1 chain; DCalpha; DC1 alpha chain
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Gene Name |
HLA-DQA1
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Target Type |
Literature-reported target
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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 andMHC 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.
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BioChemical Class |
MHC class II
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UniProt ID | ||||||
Sequence |
MILNKALMLGALALTTVMSPCGGEDIVADHVASYGVNLYQSYGPSGQYTHEFDGDEQFYV
DLGRKETVWCLPVLRQFRFDPQFALTNIAVLKHNLNSLIKRSNSTAATNEVPEVTVFSKS PVTLGQPNILICLVDNIFPPVVNITWLSNGHSVTEGVSETSFLSKSDHSFFKISYLTLLP SAEESYDCKVEHWGLDKPLLKHWEPEIPAPMSELTETVVCALGLSVGLVGIVVGTVFIIR GLRSVGASRHQGPL Click to Show/Hide
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3D Structure | Click to Show 3D Structure of This Target | AlphaFold |
Cell-based Target Expression Variations | Top | |||||
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Cell-based Target Expression Variations |
Different Human System Profiles of Target | Top |
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Human Similarity Proteins
of target is determined by comparing the sequence similarity of all human proteins with the target based on BLAST. The similarity proteins for a target are defined as the proteins with E-value < 0.005 and outside the protein families of the target.
A target that has fewer human similarity proteins outside its family is commonly regarded to possess a greater capacity to avoid undesired interactions and thus increase the possibility of finding successful drugs
(Brief Bioinform, 21: 649-662, 2020).
Human Tissue Distribution
of target is determined from a proteomics study that quantified more than 12,000 genes across 32 normal human tissues. Tissue Specificity (TS) score was used to define the enrichment of target across tissues.
The distribution of targets among different tissues or organs need to be taken into consideration when assessing the target druggability, as it is generally accepted that the wider the target distribution, the greater the concern over potential adverse effects
(Nat Rev Drug Discov, 20: 64-81, 2021).
Human Pathway Affiliation
of target is determined by the life-essential pathways provided on KEGG database. The target-affiliated pathways were defined based on the following two criteria (a) the pathways of the studied target should be life-essential for both healthy individuals and patients, and (b) the studied target should occupy an upstream position in the pathways and therefore had the ability to regulate biological function.
Targets involved in a fewer pathways have greater likelihood to be successfully developed, while those associated with more human pathways increase the chance of undesirable interferences with other human processes
(Pharmacol Rev, 58: 259-279, 2006).
Human Similarity Proteins
Human Tissue Distribution
Human Pathway Affiliation
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There is no similarity protein (E value < 0.005) for this target
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Note:
If a protein has TS (tissue specficity) scores at least in one tissue >= 2.5, this protein is called tissue-enriched (including tissue-enriched-but-not-specific and tissue-specific). In the plots, the vertical lines are at thresholds 2.5 and 4.
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KEGG Pathway | Pathway ID | Affiliated Target | Pathway Map |
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Phagosome | hsa04145 | Affiliated Target |
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Class: Cellular Processes => Transport and catabolism | Pathway Hierarchy | ||
Cell adhesion molecules | hsa04514 | Affiliated Target |
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Class: Environmental Information Processing => Signaling molecules and interaction | Pathway Hierarchy | ||
Antigen processing and presentation | hsa04612 | Affiliated Target |
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Class: Organismal Systems => Immune system | Pathway Hierarchy | ||
Hematopoietic cell lineage | hsa04640 | Affiliated Target |
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Class: Organismal Systems => Immune system | Pathway Hierarchy | ||
Th1 and Th2 cell differentiation | hsa04658 | Affiliated Target |
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Class: Organismal Systems => Immune system | Pathway Hierarchy | ||
Th17 cell differentiation | hsa04659 | Affiliated Target |
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Class: Organismal Systems => Immune system | Pathway Hierarchy | ||
Intestinal immune network for IgA production | hsa04672 | Affiliated Target |
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Class: Organismal Systems => Immune system | Pathway Hierarchy | ||
Click to Show/Hide the Information of Affiliated Human Pathways |
References | Top | |||||
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REF 1 | Preferential presentation of herpes simplex virus T-cell antigen by HLA DQA1*0501/DQB1*0201 in comparison to HLA DQA1*0201/DQB1*0201. Hum Immunol. 1997 Apr 1;53(2):195-205. |
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