Lipid Traffic In Animal Cells

Lipid and fatty acid composition of different fractions from rat urinary transitional epithelium

“…GSL content was previously reported (9,13,14); and nervonic acid (24:1n-9), a characteristic compound of monohexosyl GSL (cerebrosides), was detected in Cyt (enriched in Golgi marker enzyme, see Table 1) and PM fractions. The enrichment of GSL and the lack of concentration of SPH in PM fraction would indicate, contrary to the concept on their intracellular traffic to the surface (27), that these two lipids are sorted in different domains. This may represent another particular characteristic of the lipid transport of this mammal's TE.…”

“…This implies that cholesterol and SPH are sorted and concentrated together in their pathway to the trans-Golgi and further out (27). Interestingly, this does not seem to be the case for urothelial TE since cholesterol and SPH contents in total TE (37 and 6.5, respectively, Table 3) were about the same as those in PM (40 and 8.5, respectively; Refs.…”

“…It is known that PM are typically enriched in cholesterol, sphingomyelin (SPH), and phosphatidylserine (PS), whereas PC is decreased in comparison to those values in ER (27). This implies that cholesterol and SPH are sorted and concentrated together in their pathway to the trans-Golgi and further out (27).…”

The Endoplasmic Reticulum Ca2+-pump SERCA2b Interacts with G Protein-coupled Receptors and Enhances their Expression at the Cell Surface

“…46 In addition, undisturbed Ca 2+ homeostasis and local lipid asymmetry may play a role in correct integration of membrane proteins, as the proteins that are targeted to the plasma membrane face the problem that they must fold properly and become correctly integrated into the lipid bilayer that is thinner and has a different lipid composition than the plasma membrane. 7,47 This may be even more critical for integral membrane proteins that appear to fold and mature slowly and inefficiently, as is the case for a few GPCRs, like the hδOR and rLHR. 18,26 The ER has a fluidic and relatively permeable and non-polarized lipid bilayer, 48 and the 10 4 -fold Ca 2+ -gradient across the membrane requires continuous function of SERCA2b.…”

Rapid transmembrane diffusion of ceramide and dihydroceramide spin-labelled analogues in the liquid ordered phase

“…In general, the content of cholesterol in eukaryotic cellular membranes increases from the organelle membranes to the plasma membrane: The cholesterol-to-lipid molar ratio in the ER is small compared to that of the Golgi membrane, and even more so compared to the plasma membrane [18]. Cholesterol reduces membrane permeability to ions and modifies the physical properties of cell membranes by being in particular responsible for the formation of rafts [19].…”