Interaction of calmodulin with the cytoplasmic domain of platelet glycoprotein VI

Robert K. Andrews, Katsue Suzuki-Inoue, Yang Shen, David Tulasne, Stephen P. Watson, Michael C. Berndt

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The platelet collagen receptor, glycoprotein VI (GPVI), and GPIb-IX-V, which binds von Willebrand factor, initiate platelet aggregation at low or high shear stress, respectively. We recently reported that positively charged, membrane-proximal sequences within cytoplasmic domains of GPIbβ and GPV of GPIb-IX-V bind calmodulin. We now show that GPVI also binds calmodulin as follows - (1) calmodulin coimmunoprecipitated with GPVI from resting platelet lysates using an anti-GPVI IgG, but partially dissociated in platelets activated by collagen or collagen-related peptide; (2) calmodulin coprecipitated from platelet lysates with maltose-binding protein (MBP) - GPVI cytoplasmic domain fusion protein, but not MBP alone; (3) GPVI-related synthetic peptide based on the membrane-proximal sequence, His269-Pro287, induced a shift in calmodulin migration on nondenaturing gels, an assay that identifies calmodulin-binding peptides. His269-Pro287 is analogous to the calmodulin-binding sequence in GPIbβ. The novel interaction of GPVI and calmodulin may regulate aspects of GPVI function.

Original languageEnglish
Pages (from-to)4219-4221
Number of pages3
Issue number11
Publication statusPublished - 1 Jun 2002

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