Immunoblot of platelet extracts. Bovine washed platelets were boiled in SDS sample buffer and subjected to SDS-PAGE under reducing and nonreducing conditions. Protein bands were visualized by Coomassie blue staining or transferred to nitrocellulose for immunodetection with an antibody to bovine MAGP1. (A) Coomassie blue–stained gel. (B) Immunoblot analysis of proteins in panel A after transfer to nitrocellulose. Lane 1: Platelet extract under nonreducing conditions (no DTT). Lane 2: Platelet extract under reducing conditions (+ DTT). Lane 3: Semipurified bovine MAGP1 expressed by mammalian SaOS2 cells (+ DTT).