CD297 ART4 (ADP-ribosyltransferase 4), Dombrock blood group, DOK1, DO
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Non-lineage Restricted Molecule
GPI anchor
Erythroblast
Monocyte
Red Cell
T Cell
Spleen
Erythrocyte
Epithelium
Tumor Cell
38 / 38

Expression
CD297 is expressed on T and red cells, erythrocytes, erythroblasts and activated monocytes and expression is highest in the spleen but it is detected in respiratory epithelium.  Expression is detectable in the majority of gynecological tumors but not in the equivalent normal tissue. 

Structure
MOLECULAR FAMILY NAME: Belongs to the Arg-specific ADP-ribosyltransferase family.

CD297 is a GPI-anchor protein.  It contains a 29 aa signal sequence, an extracellular domain which contains a mono-ADP-ribosyltransferase (ART) motif and 5 potential N-linked glycosylation sites but does not have a transmembrane domain and cytoplasmic domain.  It is a member of a structurally related family of proteins that are expressed on the cell surface or secreted in the extracellular matrix.  The enzymatic activity has not been demonstrated experimentally.  A single amino acid variation at position 265 is the molecular basis for the Dombrock blood group.  Antigens that identified of the Dombrock blood group glycoprotein are located on the gene product, which is glycosylphosphatidylinosotol-anchored to the erythrocyte membrane.  Allelic variants, some of which lead to adverse transfusion reactions, are known.  CD297 carries the Gregory, Holley and Joseph antigens. 

MOLECULAR MASS

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION

CD296 has 5 potential N-linked glycosylation sites.

Ligands
LIGANDS AND MOLECULE ASSOCIATED WITH CD297: No information.

Function
CD297 catalyzes the transfer of a single ADP-ribose group from NAD onto an arginine of a target protein, thereby reversibly modifying the protein's function.  CD297 has been identified as the Dombrock blood group glycoprotein.  Like all ART family members, CD296 (ART1) uses NAD+ as a substrate to transfer ADP-ribose groups onto target proteins reversibly modifying their function.  CD297 is involved in the regulation of cellular metabolism. The Asn265Asp polymorphism occurs within the RGD motif.  RGDs are commonly associated with cell-cell interactions involving integrin binding.

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD297 IN INTACT ANIMAL

Dombrock blood group antigens are useful genetic markers and are sometime associated with severe hemolytic transfusion reactions due to the prosence of anti-Dombrock antibodies in adults.  CD297 is a potential therapeutic target in specific immunotherapy of HLA-A24+ gynecologic cancer patients.  CD297 expression is developmentally regulated during erythroid differentiation and occurs at highest levels in the fetal liver.



Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD297: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD297: No information.

ADDITIONAL INSIGHTS

For further information see Gubin, A. N. et al (2000) Blood 96: 2621-2627.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 420Q93070
Antibodies

Revised June 25, 2008


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