Filamin A binding to the cytoplasmic tail of GpIbα is affected only by a peptide spanning residues 557 to 575. (A) The GST-GpIbα-C-terminal construct. (B) Several cytoplasmic domain peptides examined for affects on the binding of recombinant human filamin A to the GST-GpIbα-C-terminal peptide. (C) The first 2 and last 2 lanes show that filamin A binds specifically to the GST-GpIbα-C-terminal peptide. The remaining lanes show the effects of the cytoplasmic domain peptides. (D) Effect of each peptide on recombinant filamin A binding to the GST-GpIbα-C-terminal peptide (n = 3; means + SDs; **P < .01 in comparison to no peptide by Student t test).