CD273 PDCD1LG2 (programmed cell death 1 ligand 2), B7-DC, PD-L2, PDCG1L2 
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
Type 1 glycoprotein
Dendritic Cell
T Cell
Monocyte
Macrophage
Heart
Placenta
Lung
Liver
Pancreas
Peripheral blood
B Cell
Lymphoma Cell
Mononuclear Cell
25 / 25

Expression
CD273 is expressed on dendritic cells, macrophages, activated monocytes and T cells.  Upregulation by IFN-γ stimulation occurs in monocytes and induced on dendritic cells grown from peripheral blood mononuclear cells with CSF2 and IL-4.  Expression is high in heart, placenta, pancreas, lung and liver, but is weak in spleen, lymph nodes and thymus.  It is higly expressed in primary mediastinal B-cell lymphoma cell lines and Hodgkin's lymphoma cell lines.

Structure
MOLECULAR FAMILY NAME: Belongs to the immunoglobulin gene family. 

CD273 is a single-pass type-1 254 aa glycoprotein.  It contains a 19 aa signal sequence, a 201 aa extracellular domain which contains an Ig-like C2-type domain, an Ig-like V-type domain and 5 potential N-linked glycosylation sites, a 21 aa transmembrane domain and a 32 aa cytoplasmic domain.  It is a member of the B7 family of costimulatory molecules. 

MOLECULAR MASS

POST-TRANSCRIPTIONAL MODIFICATION

Alternative splicing yields 3 different isoforms.  CD273 is found on the plasma membrane (isoform 1).  Isoform 2 consists of 183 aa and lacks residues 121-211 and is not expressed at the cell surface but is associated with the intracellular membrane.  Isoform 3 comprises 182 residues and bears a delition of residues 183-273  and significant amino acid sequence variation between 121 and 182 and is probably soluble.


POST-TRANSLATIONAL MODIFICATION: No information.

Ligands
LIGANDS AND MOLECULE ASSOCIATED WITH CD273

CD273 binds CD279 (PD1).

Function
CD273 costimulates the proliferation of T cells, principally CD4+ T cells and mediates IFN-γ production.  Several studies have provided evidence that the costimulatory functions of CD273 are unrelated to CD279 (PD-1) binding and are mediated by another as yet unidentified receptor but is a second ligand for CD279.  Ligation of CD273 by anti-CD273 IgM enhances activation of dendritic cells and augments dendritic cell stimulation of T cell responses.  This indicates CD273 is capable of signaling into the dendritic cell.  CD273 can act as a coinhibitor of the T cell function when it interacts with CD279.  A recent study has shown that T cell associated CD273 can suppress the proliferation of allo-antigen-specific T cells and IFN-γ  and IL-2 production via CD279.  Dendritic cells purified from CD273 null mice have a diminished capacity to stimulated T cell responses to nominal and allogenetic antigens.  Involvement in the costimulatory signal is essential for T lymphocyte proliferation and IFN-γ production in a CD273-independent manner.  Interaction with CD273 inhibits T cell proliferation by blocking cell cycle progression and cytokine production.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD273 IN INTACT ANIMAL

CD273 expression is a useful marker to distinguish primary mediastinal B-cell lymphoma from other diffuse large B-cell lymphomas.


Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD273: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD273: No information.

ADDITIONAL INSIGHTS

For further information see Brown, J. A. et al (2003) J. Immunol. 170: 1257-1266.



Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene80380Q9BQ51
Antibodies

Revised June 25, 2008


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