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Von Willebrand Factor
Von Willebrand factor (VWF) () is a blood glycoprotein that promotes primary hemostasis, specifically, platelet adhesion. It is deficient and/or defective in von Willebrand disease and is involved in many other diseases, including thrombotic thrombocytopenic purpura, Heyde's syndrome, and possibly hemolytic–uremic syndrome. Increased plasma levels in many cardiovascular, neoplastic, metabolic (e.g. diabetes), and connective tissue diseases are presumed to arise from adverse changes to the endothelium, and may predict an increased risk of thrombosis. Biochemistry Synthesis VWF is a large multimeric glycoprotein present in blood plasma and produced constitutively as ultra-large VWF in endothelium (in the Weibel–Palade bodies) and megakaryocytes (α-granules of platelets). Structure VWF is synthesized as a prepropeptide comprising 2813 amino acids in endothelial cells and megakaryocytes. The prepropeptide includes a 22-amino acid signal peptide (SP), a 741-amino acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is composed of blood cells suspended in blood plasma. Plasma, which constitutes 55% of blood fluid, is mostly water (92% by volume), and contains proteins, glucose, mineral ions, and hormones. The blood cells are mainly red blood cells (erythrocytes), white blood cells (leukocytes), and (in mammals) platelets (thrombocytes). The most abundant cells are red blood cells. These contain hemoglobin, which facilitates oxygen transport by reversibly binding to it, increasing its solubility. Jawed vertebrates have an adaptive immune system, based largely on white blood cells. White blood cells help to resist infections and parasites. Platelets are important in the clotting of blood. Blood is circulated around the body through blood vessels by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Factor VIII
Coagulation factor VIII (Factor VIII, FVIII, also known as anti-hemophilic factor (AHF)) is an essential blood clotting protein. In humans, it is encoded by ''F8'' gene. Defects in this gene result in hemophilia A, an X-linked bleeding disorder. Factor VIII is produced in the liver's liver sinusoid, sinusoidal cells and endothelial cells outside the liver throughout the body. This protein circulates in the bloodstream in an inactive form, bound to another molecule called von Willebrand factor, until an injury that damages blood vessels occurs. In response to injury, coagulation factor VIII is activated and separates from von Willebrand factor. The active protein (sometimes written as coagulation factor VIIIa) interacts with another coagulation factor called factor IX. This interaction sets off a chain of additional chemical reactions that form a blood clot. Factor VIII participates in blood coagulation; it is a cofactor for factor IXa, which, in the presence of Ca2+ and phosph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GpIX
Glycoprotein IX (platelet) (GP9) also known as CD42a (Cluster of Differentiation 42a), is a human gene. Platelet glycoprotein IX (GP9) is a small membrane glycoprotein found on the surface of human platelets. It forms a 1-to-1 noncovalent complex with glycoprotein Ib (GP Ib), a platelet surface membrane glycoprotein complex that functions as a receptor for von Willebrand factor (VWF; MIM 193400) (known as the Glycoprotein Ib-IX-V Receptor Complex). The main portion of the receptor is a heterodimer composed of 2 polypeptide chains, an alpha chain (GP1BA; MIM 606672) and a beta chain (GP1BB; MIM 138720), that are linked by disulfide bonds. The complete receptor complex includes noncovalent association of the alpha and beta subunits with GP9 and platelet glycoprotein V (GP5; MIM 173511). upplied by OMIMref name="entrez" /> See also * Cluster of differentiation The cluster of differentiation (also known as cluster of designation or classification determinant and often abbreviate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GpIb
Glycoprotein Ib (GPIb), also known as CD42, is a component of the GPIb-V-IX complex on platelets. The GPIb-V-IX complex binds von Willebrand factor, allowing platelet adhesion and platelet plug formation at sites of vascular injury. Glycoprotein Ibα (GPIbα) is the major ligand-binding subunit of the GPIb-V-IX complex. GPIbα is heavily glycosylated. It is deficient in the Bernard–Soulier syndrome. A gain-of-function mutation causes platelet-type von Willebrand disease Von Willebrand disease (VWD) is the most common heredity, hereditary coagulopathy, blood-clotting disorder in humans. An acquired form can sometimes result from other medical conditions. It arises from a deficiency in the quality or quantity of .... Autoantibodies against Ib/IX can be produced in immune thrombocytopenic purpura. Components include GP1BA and GP1BB. It complexes with Glycoprotein IX. References External links * Glycoproteins {{protein-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thrombin
Prothrombin (coagulation factor II) is encoded in the human by the F2-gene. It is proteolytically cleaved during the clotting process by the prothrombinase enzyme complex to form thrombin. Thrombin (Factor IIa) (, fibrose, thrombase, thrombofort, topical, thrombin-C, tropostasin, activated blood-coagulation factor II, E thrombin, beta-thrombin, gamma-thrombin) is a serine protease, that converts fibrinogen into strands of insoluble fibrin, as well as catalyzing many other coagulation-related reactions. History After the description of fibrinogen and fibrin, Alexander Schmidt hypothesised the existence of an enzyme that converts fibrinogen into fibrin in 1872. Prothrombin was discovered by Pekelharing in 1894. Physiology Synthesis Thrombin is produced by the enzymatic cleavage of two sites on prothrombin by activated Factor X (Xa). The activity of factor Xa is greatly enhanced by binding to activated Factor V (Va), termed the prothrombinase complex. Prothrombin is prod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cystine Knot
A cystine knot is a protein structural motif containing three disulfide bridges (formed from pairs of cysteine residues). The sections of polypeptide that occur between two of them form a loop through which a third disulfide bond passes, forming a rotaxane-like substructure. The cystine knot motif stabilizes protein structure and is conserved in proteins across various species. There are three types of cystine knot, which differ in the topology of the disulfide bonds: * Growth factor cystine knot (GFCK) * Inhibitor cystine knot (ICK), common in spider and snail toxins * Cyclic cystine knot, or cyclotide The growth factor cystine knot was first observed in the structure of nerve growth factor (NGF), solved by X-ray crystallography and published in 1991.; The GFCK is present in four superfamilies. These include nerve growth factor, transforming growth factor beta (TGF-β), platelet-derived growth factor, and glycoprotein hormones including human chorionic gonadotropin. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycoprotein IIb/IIIa
In biochemistry and medicine, glycoprotein IIb/IIIa (GPIIb/IIIa, also known as integrin αIIbβ3) is an integrin complex found on platelets. It is a transmembrane receptor for fibrinogen and von Willebrand factor, and aids platelet activation. The complex is formed via calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...-dependent association of gpIIb and gpIIIa, a required step in normal platelet aggregation and endothelial adherence. Platelet activation by Adenosine diphosphate, ADP (blocked by clopidogrel) leads to the aforementioned conformational change in platelet gpIIb/IIIa receptors that induces binding to fibrinogen. The gpIIb/IIIa receptor is a target of several drugs including abciximab, eptifibatide, and tirofiban. gpIIb/IIIa complex formation Once platelets are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arginylglycylaspartic Acid
Arginylglycylaspartic acid (RGD) is the most common peptide Short linear motif, motif responsible for cell adhesion to the extracellular matrix (ECM), found in species ranging from ''Drosophila melanogaster, Drosophila'' to humans. Cell adhesion proteins called integrins recognize and bind to this sequence, which is found within many matrix proteins, including fibronectin, fibrinogen, vitronectin, osteopontin, and several other adhesive extracellular matrix proteins. The discovery of RGD and elucidation of how RGD binds to integrins has led to the development of a number of drugs and diagnostics, while the peptide itself is used ubiquitously in bioengineering. Depending on the application and the integrin targeted, RGD can be chemically modified or replaced by a similar peptide which promotes cell adhesion. Discovery RGD was identified as the minimal recognition sequence within fibronectin required for cell attachment by Ruoslahti and Pierschbacher in the early 1980s. To do this, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ADAMTS13
ADAMTS13 (''a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13'')—also known as ''von Willebrand factor-cleaving protease'' (VWFCP)—is a zinc-containing metalloprotease enzyme that cleaves von Willebrand factor (vWf), a large protein involved in blood clotting. It is secreted into the blood and degrades large vWf multimers, decreasing their activity, hence ''ADAMTS13'' acts to reduce thrombus formation. Genetics The ''ADAMTS13'' gene maps to the ninth chromosome (9q34). Discovery Since 1982 it had been known that thrombotic thrombocytopenic purpura (TTP), one of the microangiopathic hemolytic anemias (see below), was characterized in its familial form by the presence in plasma of unusually large von Willebrand factor multimers (ULVWF). In 1994, vWF was shown to be cleaved between a tyrosine at position 1605 and a methionine at 1606 by a plasma metalloprotease enzyme when it was exposed to high levels of shear stress. In 1996, two research grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osteoprotegerin
Osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor (OCIF) or tumour necrosis factor receptor superfamily member 11B (TNFRSF11B), is a cytokine receptor of the tumour necrosis factor (TNF) receptor superfamily encoded by the ''TNFRSF11B'' gene. OPG was first discovered as a novel secreted TNFR related protein that played a role in the regulation of bone density and later for its role as a decoy receptor for receptor activator of nuclear factor kappa-B ligand ( RANKL). OPG also binds to TNF-related apoptosis-inducing ligand ( TRAIL) and inhibits TRAIL induced apoptosis of specific cells, including tumour cells. Other OPG ligands include syndecan-1, glycosaminoglycans, von Willebrand factor, and factor VIII-von Willebrand factor complex. OPG has been identified as having a role in tumour growth and metastasis, heart disease, immune system development and signalling, mental health, diabetes, and the prevention of pre-eclampsia and osteoporosis during pre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
