PMID: 3771533Oct 25, 1986Paper

Crossed immunoelectrophoresis of human platelet membranes. Effect of charge on association and dissociation of the glycoprotein GPIIb-GPIIIa membrane complex.

The Journal of Biological Chemistry
S KarpatkinD Dorfman

Abstract

The mechanism of association of the human platelet membrane GPIIb-GPIIIa-Ca2+ complex was studied by treating solubilized membranes with various enzymes and cationic peptides and by studying the binding of 45Ca2+ and 125I-fibrinogen before and after dissociation with EGTA and association with Ca2+. Neuraminidase shifted the complex cathodally (presumably due to cleavage of negatively charged domains), whereas trypsin had no such effect. The EGTA-dissociated complex was almost completely reassociated with neuraminidase or the cationic peptide, tetralysine. The monoclonal antibody 10E5, which specifically binds to the Ca2+-associated complex (not to its dissociated components), also bound to the neuraminidase-associated complex. Thus, Ca2+ is not necessary for the association of the complex. Neuraminidase treatment of washed intact platelets resulted in a cathodal shift of the membrane Triton X-100-extracted associated complex with no effect on its ability to dissociate in the presence of EGTA. Neuraminidase treatment of ADP-perturbed washed platelets also resulted in a cathodal shift of the associated complex; however, dissociation with EGTA was inhibited. Thus, critical neuraminidase-sensitive components of the complex (sialic ...Continue Reading

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