Expression and disulfide bond formation of αIIbβ3 integrins on CHO-K1 cells. (A) Immunofluorescence flow cytometry of CHO-K1 transfectants. CHO-K1 cells stably transfected with the wild-type (WT) or cysteine mutant (α968C/β693C) αIIbβ3 integrin were immunostained with 10E5 (anti-αIIb), AP3 (anti-β3), and LM609 (anti-αVβ3 complex) and detected by flow cytometry (–). Mock-transfected CHO-K1 cells were used as a control. Cells immunostained with X63 control IgG are shown (----). (B) Immunoprecipitation. Lysates from (35)S-labeled CHO-K1 stable transfectants were immunoprecipitated with mAb 10E5 (anti-αIIb). The precipitates of WT or α968C/β693C mutant were treated with nonreducing or reducing loading buffer and subjected to 7.5% SDS-PAGE. Bands of αIIb (α), β3 (β), and αIIb/β3 (α/β) heterodimer are indicated. Positions of protein molecular size markers (in kDa) are shown on the left.