Biological membranes, such as those surrounding animal cells, are made up of lipids and proteins. Because these molecules do not usually mix well, they are distributed within different regions of the membrane. This segregation is achieved in a number of ways, including the formation of domains based on particular lipids such as cholesterol or sphingomyelin (SM). These two lipids are required for the generation of cholesterol-dependent raft domains, which are necessary for signaling within the plasma membrane. However, it was not clear how SMs interacted with other molecules of raft domains, mainly because of the lack of a suitable synthetic probe of SM. Now, research led by Osaka University in collaboration with JST ERATO Lipid Active Structure Project has developed new fluorescent synthetic molecules (analogs) that structurally mimic SMs and can be studied in live cells. The study was reported in Journal of Cell Biology.