CD42d GP5 (glycoprotein V platelet), GPV (platelet glycoprotein)
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Lineage Restricted Molecule
Type 1 glycoprotein
Platelet
Megakaryocyte
82 / 82

Expression
CD42d expression is restricted on platelets and megakaryocytes.



Structure
MOLECULAR FAMILY NAME: Belongs to the mucin family.

CD42d is a single-pass type-1 glycoprotein.  It contains a 504 aa N-terminal extracellular domain which contains 14 leucine-rich sequences flanked by consensus flanking sequences of 22 aa, a thrombin cleavage site and cleavage sites for other physiological relevant proteases such as calpain and 8 potential N-glycosylation sites and may have 2-3 O-glycosylation sites in the region close to the membrane, a 24 aa transmembrane domain and a 16 aa cytoplamsic domain.  CD42d belongs to the mucin family which is part of the leucine-rich repeat (LRR) family.  It forms a non-covalent complex with CD42a, ba and cb.   

MOLECULAR MASS
Cell Type Unreduced Reduced Comment
Platelets 82 kDa 82 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION

There are 8 potential N-glycosylation sites and, possibly, in the region near to the membrane, 2 or 3 O-glycosylation sites.

Ligands
CD42 complex binds von Willebrand factor the thrombin.

LIGANDS AND MOLECULES ASSOCIATED WITH CD42d
Molecule Comment
CD42a
CD42d forms a complex with CD42a, b and c. Transfection experiments showed that co-transfection of CD42d is not required for expression of the CD42a-c complex, whereas the CD42a, b and c subunits were all indispensable for efficient expression of CD42d

CD42b
CD42d forms a complex with CD42a, b and c. Transfection experiments showed that co-transfection of CD42d is not required for expression of the CD42a-c complex, whereas the CD42a, b and c subunits were all indispensable for efficient expression of CD42d
CD42c

CD42d forms a complex with CD42a, b and c. Transfection experiments showed that co-transfection of CD42d is not required for expression of the CD42a-c complex, whereas the CD42a, b and c subunits were all indispensable for efficient expression of CD42d




Function
CD42d combines with CD42a, CD42b and CD42c to form a CD42 complex, which functions as a receptor for von Willebrand factor.  The receptor mediates the adhesion of platelets to injured vascular surfaces in the arterial circulation, a critical initiating event in homostasis.  The complex mediates adhesion of platelets to subendothelial matrices, which are exposed upon damage to the endothelium, at high shear rates.  It also amplifies the platelet response to thrombin during platelet activation where thrombin is involved.

BIOCHEMICAL ACTIVITY

The CD42a-d complex serves as receptor for von Willebrand factor (vWf) and thrombin.

DISEASE RELEVANCE AND FUNCTION OF CD42d IN INTACT ANIMAL

Mutations in CD42d  gives rise to Bernard-Soulier syndrome (BSS), which is a bleeding disorder and with the presence of giant platelets, is characterized by the absence or very reduced expression of members of the GPIb/IX/V CD42a-d complex.  So far mutations have been found in the genes encoding CD42a, CD42b and CD42c in patients with BSS.  CD42d mouse monoclonal antibodies are used for detection of auto- and allo-platelet antibodies with the MAIPA assay.

Comments
MOLECULAR INTERACTIONS -
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD42d
Molecule Comment
GATA-1
Ets

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD42d
Molecule Comment
Thrombin

ADDITIONAL INSIGHTS

Coexpression studies suggest that CD42d may be essential for the formation of the high affinity thrombin receptor.

Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 2814P40197
Antibodies
GB84A   View Reactivity

Revised June 25, 2008


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