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[The role of amino acid sequence between 551 and 565 in the cytoplasmic domain of glycoprotein (GP) I b alpha in the regulation of the VWF binding to GP I b alpha].

OBJECTIVE
To explore the role of the amino acids between 551 and 565 in the cytoplasmic domain of glycoprotein (GP) I b alpha in the VWF binding to GP I b alpha.


METHODS
The VWF binding to GP I b alpha induced by ristocetin was analyzed by flow cytometry, in three GP I b-IX-expressing Chinese hamster ovary (CHO) cell lines 1b9, delta 565 and delta 551, adhesion of above cells on VWF by flow chamber analysis at shear rate of 200 s(-1). The spread of GP I b-IX-expressing cells were stimulated with botrocetin on VWF-coated coverslips by confocal microscope.


RESULTS
The VWF binding to GP I b alpha was higher in delta 565 cells stimulated by ristocetin than in delta 551 or 1b9 cells. The number of delta 565 cells adhered on the VWF-coated-chamber was more than that of controls at shear rate of 200 s(-1). Moreover, the surface spreading areas of delta 565 cells were greater than that of the controls on VWF-coated coverslips.


CONCLUSIONS
The amino acids between 551 and 565 in the cytoplasmic domain of GP I b alpha regulates the VWF binding to GP I b alpha.