Synergy between dimerized GPVI and Gi-coupled signals results in aggregation without shape change.

Scanning electron microscopy (original magnification × 8000) of wild-type platelets activated with ADP (5 μM) or adrenaline (10 μM) in the absence (A-B) or presence (D-E) of JAQ1 (10 μg/mL). (C) JAQ1 alone, like adrenaline, did not induce shape change or aggregation, whereas the combination of both results in large and densely packed aggregates of platelets that had only poorly changed their shape (extrusion of short pseudopods). ADP-induced aggregates increased in size and appeared more “clasped” in the presence of JAQ1.