Analysis of integrin expression and heterodimer formation in HEK 293 cells transfected with wild-type α_Dβ₂. (A) The binding of anti-α_D-specific polyclonal antibody and anti-β₂-specific mAb IB4 to the α_Dβ₂-expressing cells was analyzed by flow cytometry. Results are presented as histograms with the logarithm of fluorescence intensity on the abscissa and the cell number on the ordinate. Control cells incubated with Alexa 488-conjugated secondary antibody are shown in the top panel. (B) Immunoprecipitation of biotin-labeled α_Dβ₂. Cells (5 × 10⁵) were labeled with biotin, lysed, and immunoprecipitated with 10 μg anti-β₂ mAb IB4. The immunoprecipitates were analyzed by Western blotting using streptavidin conjugated to horseradish peroxidase. The integrin subunits were detected using an enhanced chemiluminescent substrate and exposed to Kodak BioMax film.