Characterization of Three Alboaggregins Purified from Trimeresurus albolabris Venom

Peng, Manling; Lu, Weiqi; Kirby, Edward P.

doi:10.1055/s-0038-1648526

Cited by 48 publications

(45 citation statements)

References 6 publications

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“…Polyvinylidene fluoride (PVDF) membranes were PolyScreen from DuPont NEN (Zaventem, Belgium). Alboaggregin A was purified from Trimeresurus albolabris venom by a method similar to that of Peng et al 17 …”

Section: Methodsmentioning

confidence: 99%

Echicetin, a GPIb-binding snake C-type lectin from Echis carinatus, also contains a binding site for IgMκ responsible for platelet agglutination in plasma and inducing signal transduction

Navdaev

Dörmann

Clemetson

et al. 2001

Blood

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Section: Methodsmentioning

confidence: 99%

Echicetin, a GPIb-binding snake C-type lectin from Echis carinatus, also contains a binding site for IgMκ responsible for platelet agglutination in plasma and inducing signal transduction

Navdaev

Dörmann

Clemetson

et al. 2001

Blood

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“…Unless otherwise specified, all platelet stimulation occurred in the presence of 1 mM EGTA. Alboaggregin A was prepared from crude T. albolabris venom as described previously (28,29) by ion exchange chromatography. Alboaggregin A was used at 3.5 g/ml, a concentration previously determined to be the EC 50 value for induction of 5-HT release (19).…”

Section: Preparation and Stimulation Of Human Plateletsmentioning

confidence: 99%

Interaction of Bruton's Tyrosine Kinase and Protein Kinase Cθ in Platelets

Crosby

Poole

2002

Journal of Biological Chemistry

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The nonreceptor Bruton's tyrosine kinase (Btk) has been previously shown to associate physically and functionally with members of the protein kinase C (PKC) family of serine/threonine kinases in a variety of cell types. Here we show evidence for a novel interaction between Btk and PKC in platelets activated through the adhesion receptors GP Ib-V-IX and GP VI. Alboaggregin A, a snake venom component capable of activating both receptors in combination, leads to tyrosine phosphorylation of Btk downstream of Src family kinases. Inhibition of Btk by the selective antagonist LFM-A13 causes a reduction in calcium entry, although secretion of 5-hydroxytryptamine is potentiated. Btk is also phosphorylated on threonine residues in a PKC-dependent manner and associates with PKC upon platelet activation by either alboaggregin A or activation of GP Ib-V-IX alone by von Willebrand factor/ristocetin. PKC in turn becomes tyrosine-phosphorylated in a manner dependent upon Src family and Btk kinase activity. Inhibition of Btk activity by LFM-A13 leads to enhancement of PKC activity, whereas nonselective inhibition of PKC activity by bisindolylmaleimide I leads to reduction in Btk activity. We propose a reciprocal feedback interaction between Btk and PKC in platelets, in which PKC positively modulates activity of Btk, which in turn feeds back negatively upon PKC.Bruton's tyrosine kinase (Btk) 1 is a member of the Tec family of nonreceptor tyrosine kinases, which includes Itk, Tec, Txk, and Bmx and is of pathological significance when deficient or functionally mutated in the severe immunodeficiency syndrome X-linked agammaglobulinemia (1). Tec family kinases are characterized by a C-terminal proline-rich region, Src homology 1, 2, and 3 domains, and an N-terminal pleckstrin homology (PH) and Tec homology domains. Btk is expressed in cells of hematopoietic origin including platelets and has been shown to mediate calcium influx in these cells (2-5). Btk has been shown to play an important role in platelet activation by collagen because collagen stimulation induces tyrosine phosphorylation and activation of Btk (6), and in platelets lacking functional Btk, collagen-induced platelet aggregation and calcium influx are impaired significantly (7). The activity of Btk is controlled by several factors including phosphorylation. Btk has been shown to be phosphorylated at tyrosine 551 within the catalytic domain by associated Src family kinases, leading to autophosphorylation at tyrosine 223 within the Src homology 3 domain, which is necessary for full activation (8 -11). It has also been shown that for full activation, the PH domain of Btk must interact with the lipid product of phosphatidylinositol 3-kinase, phosphatidylinositol 3,4,5-trisphosphate (12). It has been hypothesized that the function of this interaction is to recruit Btk from the cytosol to the plasma membrane, where it can be subsequently activated by Src family kinases.Btk has been shown to associate with members of the protein kinase C (PKC) family of serine/threonine kina...

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“…Another example of a snake C-type lectin that binds to more than one ligand is alboaggregin A [4,[33][34][35]. The situation is slightly more complicated here because this is a dimeric heterodimer or tetramer and probably binding sites are present on both heterodimers.…”

Section: Ligand Binding Sitesmentioning

confidence: 99%

“…The situation is slightly more complicated here because this is a dimeric heterodimer or tetramer and probably binding sites are present on both heterodimers. Alboaggregin A was first identified as a GPIb-binding protein from Trimeresurus albolabris venom as well as alboaggregins B and C [33]. However, unlike the two others it showed much stronger activating effects on platelets.…”

Section: Ligand Binding Sitesmentioning

confidence: 99%

Multifunctional Snake C-Type Lectins Affecting Platelets

Clemetson

Navdaev²,

Dörmann³

et al. 2001

Pathophysiol Haemos Thromb

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Snake venoms contain a wide range of components, many of which affect haemostasis by activation or inhibition of platelets or coagulation factors. They can be classified into groups based on structure and mode of action. One group is the snake C-type lectins, so called because of the typical folding which closely resembles that found in classical C-type lectins, such as selectins and mannose-binding proteins. Unlike the classic C-type lectins, those from snakes are generally heterodimeric with two subunits, α and β. Some are multimeric heterodimers. The subunits have homologous sequences and are generally linked by a disulphide bond as well as by swapping loops. One of the first C-type lectins with a defined function was echicetin which was demonstrated to bind to platelet GPIb and block several functions of this receptor. Since then, many proteins with similar structure have been reported to act on platelet receptors or coagulation factors and several have been crystallized. These proteins were thought to be specific for a single platelet receptor or coagulation factor, i.e. they had only one receptor per heterodimer. Recent studies show that most of these C-type lectins have binding sites for more than one ligand and have complex mechanisms of action.

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Characterization of Three Alboaggregins Purified from Trimeresurus albolabris Venom

Cited by 48 publications

References 6 publications

Echicetin, a GPIb-binding snake C-type lectin from Echis carinatus, also contains a binding site for IgMκ responsible for platelet agglutination in plasma and inducing signal transduction

Echicetin, a GPIb-binding snake C-type lectin from Echis carinatus, also contains a binding site for IgMκ responsible for platelet agglutination in plasma and inducing signal transduction

Interaction of Bruton's Tyrosine Kinase and Protein Kinase Cθ in Platelets

Multifunctional Snake C-Type Lectins Affecting Platelets

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