Sphingolipid Biochemistry

Abstract

The idea that glycosphingolipids (or, briefly, glycolipids) are ubiquitous components of plasma membrane and display cell type-specific patterns perhaps stemmed from the classical studies on glycolipids of erythrocyte membranes.(1,2) Subsequently, plasma membranes of various animal cells were successfully isolated and analyzed; all were characterized by their much higher content of glycolipid than was found in intracellular membranes.(3–8) It is generally assumed that glycolipids are present at the outer leaflet of the plasma membrane bilayer, although this assumption is based only on experiments with surface-labeling by galactose oxidase-NaB[3H]4 of intact and lysed erythrocyte membranes and inside-out vesicles.(9,10) Obviously, further extensive studies of the organization of glycolipid in other eukaryotic cell membranes are necessary. Interestingly, the majority of neutral glycolipids present in plasma membranes are cryptic (see Section 4.2.1).