Single-molecule study of interactions among cell membrane components

Raft domains have been drawing extensive attention as a possible signaling platform in the plasma membrane, where GPI-anchored proteins, cholesterol, glycosphingolipids, and lipid-anchored signaling molecules are concentrated. However, the raft domains in the plasma membrane before stimulation are very obscure objects. 

Furthermore, how rafts are involved in the signal transduction has been hardly known. To reveal the mechanism of raft signaling, we have investigated the interactions between raftophilic molecules by single molecule imaging.
We were the first to simultaneously observe single molecules of two different types of molecules in living cell plasma membranes. We have also established the methodologies on how to observe receptor dimers in the cell plasma membranes, and how to observe the rafts at the steady state before stimulation. More recently, we have tracked single molecules at temporal and spatial resolutions of 50 us and 15 nm.