HLA class I histocompatibility antigen, alpha chain G - P17693 (HLAG_HUMAN)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P17693: 9
 
Function
Isoform 1: Non-classical major histocompatibility class Ib molecule involved in immune regulatory processes at the maternal-fetal interface (PubMed:23184984, PubMed:29262349, PubMed:19304799). In complex with B2M/beta-2 microglobulin binds a limited repertoire of nonamer self-peptides derived from intracellular proteins including histones and ribosomal proteins (PubMed:7584149, PubMed:8805247). Peptide-bound HLA-G-B2M complex acts as a ligand for inhibitory/activating KIR2DL4, LILRB1 and LILRB2 receptors on uterine immune cells to promote fetal development while maintaining maternal-fetal tolerance (PubMed:23184984, PubMed:29262349, PubMed:16366734, PubMed:19304799, PubMed:20448110, PubMed:27859042). Upon interaction with KIR2DL4 and LILRB1 receptors on decidual NK cells, it triggers NK cell senescence-associated secretory phenotype as a molecular switch to promote vascular remodeling and fetal growth in early pregnancy (PubMed:23184984, PubMed:29262349, PubMed:16366734, PubMed:19304799). Through interaction with KIR2DL4 receptor on decidual macrophages induces proinflammatory cytokine production mainly associated with tissue remodeling (PubMed:19304799). Through interaction with LILRB2 receptor triggers differentiation of type 1 regulatory T cells and myeloid-derived suppressor cells, both of which actively maintain maternal-fetal tolerance (PubMed:20448110, PubMed:27859042). May play a role in balancing tolerance and antiviral-immunity at maternal-fetal interface by keeping in check the effector functions of NK, CD8+ T cells and B cells (PubMed:10190900, PubMed:11290782, PubMed:24453251). Reprograms B cells toward an immune suppressive phenotype via LILRB1 (PubMed:24453251). May induce immune activation/suppression via intercellular membrane transfer (trogocytosis), likely enabling interaction with KIR2DL4, which resides mostly in endosomes (PubMed:20179272, PubMed:26460007). Through interaction with the inhibitory receptor CD160 on endothelial cells may control angiogenesis in immune privileged sites (PubMed:16809620). UniProt
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Subunit Structure
Forms a heterotrimer with B2M and a self-peptide (peptide-bound HLA-G-B2M) (PubMed:7584149, PubMed:8805247). HLA-G-B2M complex interacts with components of the antigen processing machinery TAPBP and TAP1-TAP2 complex; this interaction is required for loading of high affinity peptides and heterotrimer translocation to the cell surface (PubMed:7584149). Interacts with CALCR; this interaction is required for appropriate folding (PubMed:9640257). Interacts with COPB1; this interaction mediates the endoplasmic reticulum (ER) retrieval of HLA-G-B2M complexes that bind low affinity peptides (PubMed:11520457, PubMed:12582157). On the cell surface, peptide-bound HLA-G-B2M molecules (referred to as monomers) can form disulfide-linked homomultimers, homodimers and homotrimers (PubMed:12454284, PubMed:12874224, PubMed:16455647). Interacts with KIR2DL4; this interaction is direct (PubMed:10190900, PubMed:16366734). Interacts with LILRB1 and LILRB2 receptors; this interaction is direct (PubMed:16455647, PubMed:16366734, PubMed:17056715, PubMed:12853576). Interacts with CD160; this interactions is direct (PubMed:16809620). Interacts with CD8A homodimer; this interaction is direct and might down-regulate T cell receptor signaling (PubMed:12853576). Isoform 2: Forms a non-disulfide-linked homodimer and interacts with LILRB2 (PubMed:28348268). UniProt
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Data in green originates from UniProtKB  
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Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
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Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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