Biomaterial Database

Compartmental organization of the synthesis of GM3, GD3, and GM2 in golgi membranes from neural retina cells. 1997

M K Maxzúd, and H J Maccioni

Centro de Investigaciones en Química Biológica de Córdoba, CI-QUIBIC (UNC-CONICET), Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.

The relationship among lactosylceramide-(LacCer), GD3- and GM2-synthases and between the two last transferases and their common GM3 acceptor was investigated in intact Golgi membrane from chick embryo neural retina cells at early (8-days) and late (14 days) stages of the embryonic development. [3H]Gal was incorporated into endogenous glucosylceramide by incubation of Golgi membranes with UDP-[3H]Gal. Conversion of the synthesized [3H]Gal-LacCer into GM3, and of the latter into GD3, GM2 and GD2 was examined after a second incubation step with unlabeled CMP-NeuAc and/or UDP-GalNAc. With CMP-NeuAc, most [3H]Gal-LacCer was converted into GM3 in either 8- or 14- day membranes. However, while about 90% of GM3 was converted into GD3 in 8-day membranes, only about 25% followed this route in 14-day membranes. With CMP-NeuAc and UDP-GalNAc, about 90% of GM3 was used for synthesis of GM2 in 14-day membranes, while in 8-day membranes about 80% followed the route to GD3, and a part to GD2. Performing the second incubation step in the presence of increasing detergent concentrations showed that conversion of GM3 to GM2 was inhibited at concentrations lower than those required for inhibition of LacCer to GM3 conversion. Taken together, results indicate that transfer steps leading to synthesis of GM3, GD3, GM2 and GD2 from LacCer are functionally coupled in the Golgi membranes, and that GD3- and GM2-synthases compete in a common compartment for using a fraction of GM3 as substrate. In this competition, the relative activities of the transferases and their relative saturation with the respective donor sugar nucleotides, are important factors influencing conversion of GM3 toward either GD3 or GM2.

UI	MeSH Term	Description	Entries
D007425	Intracellular Membranes	Thin structures that encapsulate subcellular structures or ORGANELLES in EUKARYOTIC CELLS. They include a variety of membranes associated with the CELL NUCLEUS; the MITOCHONDRIA; the GOLGI APPARATUS; the ENDOPLASMIC RETICULUM; LYSOSOMES; PLASTIDS; and VACUOLES.	Membranes, Intracellular,Intracellular Membrane,Membrane, Intracellular
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D007790	Lactosylceramides	Glycosphingolipids which contain as their polar head group a lactose moiety bound in glycosidic linkage to the hydroxyl group of ceramide. Their accumulation in tissue, due to a defect in lactosylceramide beta-galactosidase, is the cause of lactosylceramidosis.	Lactosyl Ceramides,Ceramides, Lactosyl
D012160	Retina	The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.	Ora Serrata
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
D003902	Detergents	Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.	Cleansing Agents,Detergent Pods,Laundry Detergent Pods,Laundry Pods,Syndet,Synthetic Detergent,Agent, Cleansing,Agents, Cleansing,Cleansing Agent,Detergent,Detergent Pod,Detergent Pod, Laundry,Detergent Pods, Laundry,Detergent, Synthetic,Detergents, Synthetic,Laundry Detergent Pod,Laundry Pod,Pod, Detergent,Pod, Laundry,Pod, Laundry Detergent,Pods, Detergent,Pods, Laundry,Pods, Laundry Detergent,Synthetic Detergents
D005678	G(M2) Ganglioside	A glycosphingolipid that accumulates due to a deficiency of hexosaminidase A or B (BETA-N-ACETYLHEXOSAMINIDASES), or GM2 activator protein, resulting in GANGLIOSIDOSES, heredity metabolic disorders that include TAY-SACHS DISEASE and SANDHOFF DISEASE.	GM2 Ganglioside,Tay-Sachs Disease Ganglioside,Ganglioside GM2,GM2, Ganglioside,Ganglioside, GM2,Ganglioside, Tay-Sachs Disease,Tay Sachs Disease Ganglioside
D005679	G(M3) Ganglioside	A ganglioside present in abnormally large amounts in the brain and liver due to a deficient biosynthetic enzyme, G(M3):UDP-N-acetylgalactosaminyltransferase. Deficiency of this enzyme prevents the formation of G(M2) ganglioside from G(M3) ganglioside and is the cause of an anabolic sphingolipidosis.	Hematoside,Sialyllactosylceramide,Ganglioside GM3,II3NeuAcLacCer,Sialyl Lactosylceramide,GM3, Ganglioside,Lactosylceramide, Sialyl
D005690	Galactose	An aldohexose that occurs naturally in the D-form in lactose, cerebrosides, gangliosides, and mucoproteins. Deficiency of galactosyl-1-phosphate uridyltransferase (GALACTOSE-1-PHOSPHATE URIDYL-TRANSFERASE DEFICIENCY DISEASE) causes an error in galactose metabolism called GALACTOSEMIA, resulting in elevations of galactose in the blood.	D-Galactose,Galactopyranose,Galactopyranoside,D Galactose
D005732	Gangliosides	A subclass of ACIDIC GLYCOSPHINGOLIPIDS. They contain one or more sialic acid (N-ACETYLNEURAMINIC ACID) residues. Using the Svennerholm system of abbrevations, gangliosides are designated G for ganglioside, plus subscript M, D, or T for mono-, di-, or trisialo, respectively, the subscript letter being followed by a subscript arabic numeral to indicated sequence of migration in thin-layer chromatograms. (From Oxford Dictionary of Biochemistry and Molecular Biology, 1997)	Ganglioside,Sialoglycosphingolipids