Glycosphingolipid-cholesterol formed as microdomains in cell membranes have been proposed to function as rafts for the attachment of specific proteins including glycosylphosphatidylinositol-anchored proteins, glycoproteins and proteoglycans. The microdomains are postulated to be involved in transmembrane signaling. Here, the functional roles of glycoconjugates in the physical properties of these microdomains, as well as in signal transduction are discussed.