Immunoblot analyses of GPIIIa (nonreduced) and GPIIb (reduced). SDS-solubilized platelets (1 μL of 5 × 107platelets/mL) were electrophoresed into a 7.5% polyacrylamide gel, electrotransferred onto PVDF membranes, and developed as previously described.31 (A) Control, patient, and two other GT patient samples with mutations in GPIIIa (I-J: Iraqi-Jewish) and GPIIb (Arab)44 were run under nonreduced conditions. The membranes were incubated with the anti-GPIIIa specific murine MoAb, 7H2.29 The arrow indicates the position of GPIIIa. (B) Two patient samples prepared on different dates (January 1990 and February 1995) and a control sample were run under reduced conditions. The membranes were incubated with the anti-GPIIb heavy chain specific murine MoAb, PMI-1.32 33 The solid arrow indicates the position of proGPIIb, the open arrow, mature processed GPIIb, and the arrow head an abnormally migrating fragment.