Aggretin, a heterodimeric C-type lectin from Calloselasma rhodostoma (malayan pit viper), stimulates platelets by binding to alpha 2beta 1 integrin and glycoprotein Ib, activating Syk and phospholipase Cgamma 2, but does not involve the glycoprotein VI/Fc receptor gamma chain collagen receptor

Navdaev, A; Clemetson, JM; Polgar, J; Kehrel, BE; Glauner, M; Magnenat, E; Wells, TN; Clemetson, KJ (2001). Aggretin, a heterodimeric C-type lectin from Calloselasma rhodostoma (malayan pit viper), stimulates platelets by binding to alpha 2beta 1 integrin and glycoprotein Ib, activating Syk and phospholipase Cgamma 2, but does not involve the glycoprotein VI/Fc receptor gamma chain collagen receptor. Journal of biological chemistry, 24(276), pp. 20882-9. Bethesda, Md.: American Society for Biochemistry and Molecular Biology 10.1074/jbc.M101585200

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Aggretin, a potent platelet activator, was isolated from Calloselasma rhodostoma venom, and 30-amino acid N-terminal sequences of both subunits were determined. Aggretin belongs to the heterodimeric snake C-type lectin family and is thought to activate platelets by binding to platelet glycoprotein alpha(2)beta(1). We now show that binding to glycoprotein (GP) Ib is also required. Aggretin-induced platelet activation was inhibited by a monoclonal antibody to GPIb as well as by antibodies to alpha(2)beta(1). Binding of both of these platelet receptors to aggretin was confirmed by affinity chromatography. No binding of other major platelet membrane glycoproteins, in particular GPVI, to aggretin was detected. Aggretin also activates platelets from Fc receptor gamma chain (Fcgamma)-deficient mice to a greater extent than those from normal control mice, showing that it does not use the GPVI/Fcgamma pathway. Platelets from Fcgamma-deficient mice expressed fibrinogen receptors normally in response to collagen, although they did not aggregate, indicating that these platelets may partly compensate via other receptors including alpha(2)beta(1) or GPIb for the lack of the Fcgamma pathway. Signaling by aggretin involves a dose-dependent lag phase followed by rapid tyrosine phosphorylation of a number of proteins. Among these are p72(SYK), p125(FAK), and PLCgamma2, whereas, in comparison with collagen and convulxin, the Fcgamma subunit neither is phosphorylated nor coprecipitates with p72(SYK). This supports an independent, GPIb- and integrin-based pathway for activation of p72(SYK) not involving the Fcgamma receptor.

Item Type:	Journal Article (Original Article)
Division/Institute:	04 Faculty of Medicine > Pre-clinic Human Medicine > Theodor Kocher Institute
UniBE Contributor:	Clemetson, Kenneth John
ISSN:	0021-9258
ISBN:	11287424
Publisher:	American Society for Biochemistry and Molecular Biology
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:52
Last Modified:	05 Dec 2022 14:16
Publisher DOI:	10.1074/jbc.M101585200
PubMed ID:	11287424
Web of Science ID:	000169297900014
URI:	https://boris.unibe.ch/id/eprint/22200 (FactScience: 32254)