Platelet glycoprotein VI: its structure and function

Glycoprotein (GP) VI is a platelet membrane protein with a molecular weight of 62 kDa that was identified as a physiological collagen receptor from studies of patients deficient in this protein. GPVI-deficient platelets lacked specifically collagen-induced aggregation and the ability to form thrombi...

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Bibliographic Details
Published in:Thrombosis research 2004, Vol.114 (4), p.221-233
Main Authors: Moroi, Masaaki, Jung, Stephanie M.
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Blood and lymphatic vessels
Blood coagulation. Blood cells
Blood vessels and receptors
Cardiology. Vascular system
Collagen
Collagen - metabolism
Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous
FcR γ-chain
Fundamental and applied biological sciences. Psychology
GPVI
Hemorrhage - etiology
Humans
ITAM
Medical sciences
Molecular and cellular biology
Platelet
Platelet Activation
Platelet Membrane Glycoproteins - chemistry
Platelet Membrane Glycoproteins - deficiency
Platelet Membrane Glycoproteins - metabolism
Platelet Membrane Glycoproteins - physiology
Signal Transduction
Tyrosine phosphorylation
Vertebrates: cardiovascular system
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Summary:Glycoprotein (GP) VI is a platelet membrane protein with a molecular weight of 62 kDa that was identified as a physiological collagen receptor from studies of patients deficient in this protein. GPVI-deficient platelets lacked specifically collagen-induced aggregation and the ability to form thrombi on a collagen surface under flow conditions, suggesting that GPVI makes an indispensable contribution to collagen-induced platelet activation. On the platelet surface, GPVI is present as a complex with the Fc receptor (FcR) γ-chain, probably composed of two GPVI molecules and one FcR γ-chain dimer. GPVI must form such a dimeric complex to exhibit high affinity binding to collagen. The GPVI-induced activation mechanism is initiated by tyrosine phosphorylation of the immunoreceptor tyrosine-based activation motif (ITAM) of the FcR γ-chain, and then this signal is transduced to many related proteins, mainly by tyrosine phosphorylation. GPVI is widely recognized as a requisite factor for the formation of platelet aggregates on a collagen surface under blood flow. However, individuals with GPVI-deficient or null platelets do not exhibit any strong bleeding tendency. Analyzing this apparent dichotomy should provide us with a more precise understanding of the mechanism of thrombus formation.
ISSN:0049-3848
1879-2472
DOI:10.1016/j.thromres.2004.06.046