Ganglioside biosynthesis. Concentration of glycosphingolipid glycosyltransferases in Golgi apparatus from rat liver.
نویسندگان
چکیده
Golgi apparatus fractions from rat liver contained all glycosyltransferases which catalyze the in vitro biosynthesis of N-acetylneuraminylgalactosylglucosylceramide (G&, (Nacetylneuraminyl)2-galactosylglucosylceramide (GD3), N-acetylgalactosaminyl(Nacetylneuraminyl) galactosylglucosylceramide (GMz), galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosylglucosylceramide (GM& and NacetylneuraminylgalactosylNacetylgalactosaminyl (Nacetylneuraminyl)-galactosylglucosylceramide (GDla) from the corresponding precursors. Relative to total particulate fractions, these transferases were enriched 22 to 27 times in Golgi apparatus. Rough endoplasmic reticulum fractions also contained a full complement of these glycolipid glycosyltransferases; specific activities with endoplasmic reticulum were 2 to 4 times those of total particulate fractions. Plasma membrane fractions displayed negligible glycolipid glycosyltransferase activities. The combined Golgi apparatus and endoplasmic reticulum fractions accounted for more than 80% of the total homogenate glycolipid glycosyltransferase activities. The results show that gangliosides are not synthesized at the surface membrane. As with membrane glycoproteins, gangliosides appear to be glycosylated in endoplasmic reticulum and Golgi apparatus during transport to the surface membrane.
منابع مشابه
Functional organization of the Golgi apparatus in glycosphingolipid biosynthesis. Lactosylceramide and subsequent glycosphingolipids are formed in the lumen of the late Golgi.
Biosynthesis of plasma membrane sphingolipids involves the coordinate action of enzymes localized to individual compartments of the biosynthetic secretory pathway of proteins. These stations include the endoplasmic reticulum and the Golgi apparatus. Although a precise localization of all the enzymes that synthesize glycosphingolipids has not been achieved to date, it is assumed that the sequenc...
متن کاملGanglioside glycosyltransferases and newly synthesized gangliosides are excluded from detergent-insoluble complexes of Golgi membranes.
GEM (glycosphingolipid-enriched microdomains) are specialized detergent-resistant domains of the plasma membrane in which some gangliosides concentrate. Although genesis of GEM is considered to occur in the Golgi complex, where the synthesis of gangliosides also occurs, the issue concerning the incorporation of ganglioside species into GEM is still poorly understood. In this work, using Chinese...
متن کاملBoth GA2, GM2, and GD2 synthases and GM1b, GD1a, and GT1b synthases are single enzymes in Golgi vesicles from rat liver.
Competition experiments using lactosylceramide, ganglioside GM3 and ganglioside GD3 as substrates, as well as mutual inhibitors for ganglioside N-acetylgalactosaminyltransferase, in Golgi vesicles derived from rat liver suggested that N-acetylgalactosamine transfer to these three respective compounds, leading to gangliosides GA2, GM2, and GD2, respectively, is catalyzed by one enzyme. Analogous...
متن کاملRecycling of glucosylceramide and sphingosine for the biosynthesis of gangliosides and sphingomyelin in rat liver.
It was previously shown that sphingomyelin and gangliosides can be biosynthesized starting from sphingosine or sphingosine-containing fragments which originated in the course of GM1 ganglioside catabolism. In the present paper we investigated which fragments were specifically re-used for sphingomyelin and ganglioside biosynthesis in rat liver. At 30 h after intravenous injection of GM1 labelled...
متن کاملSynthesis and characterization of a new class of inhibitors of membrane-associated UDP-glycosyltransferases.
A new class of compounds designed to inhibit membrane-associated glycosyltransferases were synthesized and their biological activities were characterized in liver microsomes and human lymphoma cell lines. These inhibitors are composed of N-acyl phenylaminoalcohol derivatives linked to uridine via different spacers. One inhibitor, termed PP36 (5'-[[N-(2-decanoylamino-3-hydroxy-3-phenylpropyloxyc...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of biological chemistry
دوره 249 1 شماره
صفحات -
تاریخ انتشار 1974