CD1D

CD1d molecule
PDB rendering based on 1zt4.
Available structures PDB Ortholog search: PDBe, RCSB List of PDB id codes 1ZT4, 2PO6, 3HUJ, 3SDX, 3TZV, 3U0P, 3VWJ, 3VWK, 4EN3, 4LHU, 4MNG, 4MQ7, 4WO4
Identifiers
Symbols	CD1D ; CD1A; R3
External IDs	OMIM: 188410 MGI: 107674 HomoloGene: 1337 ChEMBL: 1649053 GeneCards: CD1D Gene
Gene ontology Molecular function • receptor activity • beta-2-microglobulin binding • lipid antigen binding • endogenous lipid antigen binding • exogenous lipid antigen binding • histone binding • cell adhesion molecule binding • lipopeptide binding Cellular component • cytoplasm • lysosomal membrane • integral component of plasma membrane • cell surface • endosome membrane Biological process • viral process • detection of bacterium • heterotypic cell-cell adhesion • positive regulation of T cell proliferation • T cell selection • innate immune response • positive regulation of innate immune response • antigen processing and presentation, endogenous lipid antigen via MHC class Ib • antigen processing and presentation, exogenous lipid antigen via MHC class Ib Sources: Amigo / QuickGO
RNA expression pattern
More reference expression data
Orthologs
Species	Human	Mouse
Entrez	912	12479
Ensembl	ENSG00000158473	ENSMUSG00000028076
UniProt	P15813	P11609
RefSeq (mRNA)	NM_001766	NM_007639
RefSeq (protein)	NP_001757	NP_031665
Location (UCSC)	Chr 1: 158.18 – 158.18 Mb	Chr 3: 87 – 87 Mb
PubMed search	[1]	[2]

CD1D is the human gene that encodes the protein CD1d, a member of the CD1 (cluster of differentiation 1) family of glycoproteins expressed on the surface of various human antigen-presenting cells. They are non-classical MHC proteins, related to the class I MHC proteins, and are involved in the presentation of lipid antigens to T cells. CD1d is the only member of the group 2 CD1 molecules.

Biological significance

CD1d-presented lipid antigens activate a special class of T cells, known as natural killer T (NKT) cells, through the interaction with the T-cell receptor present on NKT membranes. When activated, NKT cells rapidly produce Th1 and Th2 cytokines, typically represented by interferon-gamma and interleukin 4 production.

Nomenclature

CD1d is also known as R3G1

Ligands

Some of the known ligands for CD1d are:

• α-galactosylceramide (α-GalCer), a compound originally derived from the marine sponge Agelas mauritanius with no physiological role but great research utility.
• α-glucuronyl- and α-galacturonyl- ceramides, a family of compounds of microbial origin which can be found, for example, on the cell wall of Sphingomonas, a ubiquitous Gram-negative bacterium. The related β-D-glucopyranosylceramide is accumulated in antigen-presenting cells after infection, where it serves to activate invariant NKTs (iNKTs), a special kind of NKT.
• iGb3, a self antigen which has been implied in iNKT selection.
• HS44, a synthetic amino cyclitolic ceramide analogue which has less contact with the TCR, activating iNKTs in a more constrained way than α-GalCer (specially in relation to Th2 cytokines production) and thus being more interesting for therapeutic use.

CD1d tetramers

CD1d tetramers are protein constructs composed of four CD1d molecules joined together and usually fluorescently labelled, used to identify NKT cells or other CD1d-reactive cells. In particular, type I NKT cells and some type II NKT cells are stained by them. A differentiation of these two types can be obtained in human by using an antibody against the TCR Vα24 chain, which is specific of type I NKT cells.

Although they are the most widely used of CD1d oligomers, sometimes CD1d dimers (two units) or pentamers (five units) are used instead.

External links

• CD1d antigen at the US National Library of Medicine Medical Subject Headings (MeSH)