Binding of the bovine caseinoglycopeptide to the platelet membrane glycoprotein GPIb alpha

The bovine caseinoglycopeptide (residues 106-169), the C-terminal part of kappa-casein, inhibited the von Willebrand factor-dependent platelet aggregation in a dose-dependent manner. An affinity matrix made of the caseinoglycopeptide selectively bound the platelet membrane glycoprotein GPIb alpha which contains the von Willebrand factor binding site. The amino acid residues of GPIb alpha participating in the caseinoglycopeptide binding were located after residue Glu 90.