Platelet glycoprotein VI (GPVI) is a
glycoprotein
Glycoproteins are proteins which contain oligosaccharide (sugar) chains covalently attached to amino acid side-chains. The carbohydrate is attached to the protein in a cotranslational or posttranslational modification. This process is known a ...
receptor for
collagen
Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...
which is expressed in
platelets
Platelets or thrombocytes () are a part of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a blood clot. Platelets have no cell nucleus; they are fragments of cyto ...
. In humans, glycoprotein VI is encoded by the ''GP6''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
It was first cloned in 2000 by several groups including that of
Martine Jandrot-Perrus from INSERM.
Function
GPVI is a 58-kD platelet membrane glycoprotein that plays a crucial role in the collagen-induced activation and aggregation of platelets. Upon injury to the vessel wall and subsequent damage to the
endothelial
The endothelium (: endothelia) is a single layer of squamous endothelial cells that line the interior surface of blood vessels and lymphatic vessels. The endothelium forms an interface between circulating blood or lymph in the lumen and the res ...
lining, exposure of the subendothelial matrix to blood flow results in deposition of platelets. Collagen fibers are the most
thrombogenic macromolecular components of the extracellular matrix, with collagen types I, III, and VI being the major forms found in blood vessels. Platelet interaction with collagen occurs as a 2-step procedure: (1) the initial adhesion to collagen is followed by (2) an activation step leading to platelet secretion, recruitment of additional platelets, and aggregation. In physiologic conditions, the resulting
platelet plug
The platelet plug, also known as the hemostatic plug or platelet thrombus, is an aggregation of platelets formed during early stages of hemostasis in response to one or more injuries to blood vessel walls. After platelets are recruited and begin ...
is the initial hemostatic event limiting blood loss. However, exposure of collagen after rupture of
atherosclerotic plaque
An atheroma, or atheromatous plaque, is an abnormal accumulation of material in the inner layer of an arterial wall.
The material consists of mostly macrophage cells, or debris, containing lipids, calcium and a variable amount of fibrous conne ...
s is a major stimulus of thrombus formation associated with myocardial infarction or stroke.
Complete or partial deficiency of GPVI in humans is a rare condition presenting as a mild bleeding disorder.
Interactions
GPVI has been shown to
interact with
LYN.
See also
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collagen receptor
References
Further reading
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External links
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{{Coagulation