Ceramide as a second messenger: sticky solutions to sticky problems

Much discussion has recently centred around the biochemical mechanisms by which ceramide is produced in signalling pathways. Since ceramide is virtually insoluble in aqueous solutions, the biological effects of ceramide should be considered in the context of its generation within the membrane lipid bilayer. To this end, we now summarize recent data describing some biophysical properties of ceramide that are of relevance for understanding the mode of ceramide action as a second messenger, and, as a consequence, how the site(s) of ceramide generation might impact upon its role in signalling.