Characterization of the EC GpIb complex by Western blotting. Eluates from an anti-GpIbα affinity column were analyzed for (A) GpIbα and (B) GpIbβ, using affinity-purified rabbit polyclonal antibodies to glycocalicin and to a peptide sequence in platelet GpIbβ, respectively. Eluates from anti-GpIX and anti-GpV affinity columns were analyzed for (C) GpIX and (D) GpV, respectively, using MoAbs. Eluate from 2 to 3 × 10⁶ cells was loaded onto each lane. The numbers to the left of each set of gels are the molecular weights (in kilodaltons) of prestained standards. For experimental details, see Materials and Methods.