UV-C irradiation induces disulfide bridge reduction in αIIbβ3. (A) Platelets were either left untreated, irradiated with 2 doses of UV-C light, or treated with DTT, and then incubated with maleimide coupled to the fluorescent dye alexa633 to label free thiol groups. Binding of the probe was assessed by flow cytometry. Data represent the mean plus or minus SEM of 4 experiments. (B) After the treatments described under panel A, designated 1-4, platelets were incubated with BMCC to biotinylate free thiol groups. Biotinylated proteins were then precipitated with streptavidin-agarose beads. The top row shows a Western blot of the precipitates (after incubation with a MoAb specific for β3) to detect biotinylated β3 chains, the bottom row shows a Western blot with the same antibody of the total lysates. The blots shown are representative for 3 experiments. (C) Bar graph depicting the binding of the β3 antibody to the immunoblots of the precipitates as quantified on a Odyssey Infrared Imaging system and calculated as percentage of total β3 present in the lysates to correct for input differences. Data represent the mean plus or minus SEM of 3 experiments.