Ceramide-containing membranes : the interface between biophysics and biology

Abstract

Sphingolipids are important constituents of biological membranes. Ceramide, the major metabolite of this family, is involved in many cellular processes, ranging from diŠerentiation to senescence and apoptosis. Ceramide is an amphipathic molecule with a small head group that allows it to be more promiscuous within membranes than other lipids. Ceramide has a strong ability to change the physical properties of membranes through the formation of ceramide-rich domains, whose physical and morphological characteristics can be studied by a variety of biophysical techniques. While the existence of lipid domains is widely accepted, data from the literature is not consistent concerning many of their properties. We now discuss the biophysical and biological signiˆcance of two types of membrane domains (lipid rafts and ceramidedomains). In addition, we discuss other properties of ceramide, such as its ability to permeabilize the outer membrane of mitochondria. Finally, we attempt to integrate these various issues from biochemical and biophysical perspectives.