Fig. 6.
Competition of normal and mutant [674R]GPIIb for surface expression of GPIIb-IIIa complexes.
(A) CHO-IIIa cells were transiently transfected with variable amounts of normal (○) or mutant (●) [674R]GPIIb cDNAs. The surface exposure of GPIIb-IIIa heterodimers was analyzed by flow cytometry with anti-GPIIb. The results are the means ± SEM of at least 3 independent experiments in duplicate. (B) CHO-IIIa cells were cotransfected with normal to mutant [674R]GPIIb molar ratios from 0.2 to 5, and the surface expression of GPIIb-IIIa complexes was determined by flow cytometry (▪). At the normal to mutant ratio of 1, 2 μg of each plasmid was cotransfected. The estimated values (■) were obtained, assuming that, according to results on panel A, the surface expression from the translational product of both cDNAs should be additive. (C) The percentage of inhibition of surface exposure of GPIIb-IIIa was calculated from the differences between the estimated and the measured values shown in panel B.