Gangliosides, activity with

Ben-Yoseph, Y., Mitchell, D. A., Yager, R. M., and Pretzlaff, R. K., 1991, Stimulation of GM3 ganglioside activity by an activator protein in patient with mucolipidosis IV and controls. Enzyme 45 23-29. 

Because membranes components participate in nearly every cell activity their structures are also dynamic and far from the equilibrium states that are most readily understood in biophysical terms. Newly synthesized bilayer lipids are initially associated with endoplasmic reticulum (Ch.3) whereas phospholipids initially insert into the cytoplasmic leaflet while cholesterol and sphingolipids insert into the luminal endoplasmic reticulum (ER) leaflet. Glycosylation of ceramides occurs as they transit the Golgi compartments, forming cerebrosides and gangliosides in the luminal leaflet. Thus, unlike model systems, the leaflets of ER membranes are asymmetric by virtue of their mode of biosynthesis. 

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