Platelets contain general proteins of the vesicular transport machinery. HPH was probed for the presence of general vesicular transport proteins. A total of 50 and 100 μg of HPH was analyzed by SDS-PAGE followed by western blotting. Western blots were probed with antisera specific for α-SNAP, γ-SNAP, NSF, and p115/TAP. As a positive control for the specific antisera, 50 μg of bovine brain cytosol (BBC) was examined along side the HPH samples. Exposure times for each of the four antigens were not consistent and therefore should not be regarded as indicative of relative amounts.