Immunoprecipitation of _IIbβ₃from 24/12 and AM-1 cells. Cell surface was labeled with sulfo-NHS-LC-biotin and lysed with 1% Triton X-100 lysis buffer. Lysates from 24/12 cells (lanes 1 and 3) and AM-1 cells (lanes 2 and 4) were incubated with anti-_IIbβ₃ antibody, AP2, and immunoprecipitates were separated on 6% SDS-PAGE under reducing (lanes 1 and 2) or nonreducing conditions (lanes 3 and 4). After transfer, the membrane was incubated with peroxidase-conjugated avidin and developed with chemiluminescence.