CD51 ITGAV (integrin α V chain), vitronectin receptor, VNR-α chain
Molecule TypeAntigen ExpressionMolecular Weight
Min / Max
Lineage Restricted Molecule
Type 1 glycoprotein
Platelet
Hepatoma Cell
Leukocyte
Monocyte
Macrophage
Neutrophil
Muscle, Smooth
Osteoclast
B Cell
Endothelial Cell
Carcinoma Cell
Fibroblast
Neuroblastoma cell
24 / 24
125 / 125
150 / 150

Expression
CD51 in combination with CD29(αVβ1) is expressed on fibroblasts and neuroblastoma cells.  CD51 in combination CD61(aVb3) is expressed on platelets, endothelial cells, certain cultured/activated monocytes, macrophages and neutrophils, some B cells and osteoclasts and on tissues including smooth muscle cells.  CD51/β5 complex is expressed on hepatoma cells, carcinoma cells and fibroblasts.  CD51 is the most promiscuous integrin a subunit.  It can form heterodimers with CD29 (b1), CD61 (β3), b5, b6, and b8 integrin subunits in various tissues.

Structure
MOLECULAR FAMILY NAME: Belongs to the a integrin family.

CD51 is a single-pass type-1 1018 aa glycoprotein. It contains an extracellular domain which contains 13 N-glycosylation sites, 18 conserved cysteines and 4 cation binding sites, a transmembrane domain and a 32 aa cytoplasmic domain.  Integrin α chains all share a conserved sequence found at the beginning of the cytoplasmic domain just after the transmembrane domain and this motif may be involved in heterodimer formation.   It is the integrin aV subunit that combines with the CD61 b3 subunit to form CD51.  

MOLECULAR MASS
Cell Type Unreduced Reduced
150 kDa 125 kDa, 24 kDa

POST-TRANSCRIPTIONAL MODIFICATION: No information.

POST-TRANSLATIONAL MODIFICATION

CD51 does not have an I domain and is post-translationally cleaved into two disulfide-linked heavy and light chains that combine with multiple integrin β chains to form different integrins.  

Ligands
LIGANDS AND MILECULES ASSOCIATED WITH CD51 

CD51/CD61 is also known as the vitronectin receptor.  It mediates the binding of platelets to immobilized vitronectin without prior activation.  Other ligands for CD51/CD61 include RGD-containing proteins such as fibrinogen, fibronectin, von Willebrand factor (vWf), laminin, thrombospondin, bone sialoprotein (Bsp1) and the neural adhesion molecule L1, which is expressed on certain leukocytes.  CD51/CD61 also mediates cell-cell adhesion via an interaction with CD31.  It has been shown to associate on the cell surface with CD47.

Function
CD51 is the most promiscuous integrin a subunit.  It can form heterodimers with CD29 (b1), CD61 (β3), b5, b6, and b8 integrin subunits in various tissues.   CD51 is involved in cell adhesion and signal transduction.  CD51/CD61 acts as an activation-independent receptor for platelet attachment and spreading on vitronectin and other RGD-containing proteins, including matrix components.  It mediates leukocyte-endothelial cell adhesion via interaction with CD31. It has also been shown to initiate bone resorption by mediating the adhesion of osteoclasts to osteopontin, and it may play a role in angiogenesis. 

BIOCHEMICAL ACTIVITY: No information.

DISEASE RELEVANCE AND FUNCTION OF CD51 IN INTACT ANIMAL

CD51 has a role in bone metabolism, apoptosis and a possible role in infection.  Antagonists of CD51/CD61 have been shown to inhibit tumor growth by disrupting angiogenesis.



Comments
MOLECULAR INTERACTIONS-
PROTEINS AND DNA ELEMENTS WHICH REGULATE TRANSCRIPTION OF CD51: No information.

SUBSTRATES: No information.

ENZYMES WHICH MODIFY CD51: No information.


Database accession numbers
AnimalPIRSWISSPROTEMGBL/GENBANK
 
HumanEntrezgene 3685P06756
MouseP43406U14135
Antibodies

Revised June 25, 2008


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