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Ca 2+ influx mediated through the GPIIb/IIIa complex during platelet activation
Author(s) -
Yamaguchi A.,
Yamamoto N.,
Kitagawa H.,
Tanoue K.,
Yamazaki H.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)81163-8
Subject(s) - aequorin , chemistry , platelet activation , platelet , egta , thrombin , biophysics , platelet glycoprotein gpiib iiia complex , calcium , fibrinogen , biochemistry , intracellular , biology , immunology , organic chemistry
When aequorin‐loaded platelets were stimulated with thrombin, the luminescence signal of aequorin showed two peaks. From experiments with 1 mM external Ca 2+ or EGTA, both one‐half of the first peak and the entire second peak reflected the influx of Ca 2+ from the external medium, and the remaining half of the first peak reflected the mobilization of Ca 2+ from its storage site. A monoclonal antibody (TM83) that recognizes the glycoprotein IIb/IIIa (GPIIb/IIIa) complex which has binding sites for fibrinogen and the synthetic peptide GRGDSP are known to inhibit fibrinogen binding and platelet aggregation. Both eliminated the second peak of intracellular free calcium ([Ca 2+ ] i ). Similar effects were observed during activation by collagen, but not during PMA activation. It was concluded that the GPIIb/IIIa complex was intimately related to a part of the Ca 2+ influx during the activation of platelets.