ATAP2 does not detect PAR1's active conformation generated after scissile bond cleavage. (A) ATAP2 binding was quantified by cell-surface ELISA after incubation for 3 hours with the indicated agonists in cells before and after fixation with paraformaldehyde (PFA). PMA indicates phorbol myristate acetate (0.1 μg/mL). Means plus or minus SEM are shown (n = 12). (B) Cells were incubated for 3 hours with control or APC (20 nM) and biotinylated surface proteins were analyzed by Western blotting with WEDE15 or ATAP2 as indicated. A representative experiment of 3 is shown.