IDENTIFICATION OF MEMBRANE-PROTEINS OF HUMAN-BLOOD PLATELETS WITH A HYDROPHOBIC PHOTOLABEL

A photoactivable glycolipid probe, 12-(4-azido-2-nitrophenoxy)stearoyl[1-14C]glucosamine, was used to label proteins and lipids of platelet membranes. The proteins were analyzed by two-dimensional high-resolution gel electrophoresis. The labeling patterns showed that 3 membrane proteins were labeled which were not previously identified by ectolabeling (Sixma et Schiphorst, 1980). Analysis of the lipid fraction showed that phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine were labeled by the probe. The distinct labeling of phosphatidylserine strongly suggests that the probe redistributes between the 2 halves of the bilayer.