Subcellular distribution of UDP-galactose:ceramide galactosyltransferase in rat brain oligodendroglia.
Oligodendrocytes isolated from 18-19-day-old rat brain were homogenized in 0.32 M sucrose. The homogenate was centrifuged at 100,000 g for 50 min in a gradient containing 0.8, 1.05, and 1.3 M sucrose. Three discrete bands were obtained at the interfaces 0.32-0.8 (F1), 0.8-1.05 (F2), and 1.05-1.3 M (F3). The distribution of UDP-galactose:ceramide galactosyltransferase (CgalT) activity in each fraction was measured using liposomes containing normal fatty acid-containing ceramides (NFA-CgalT activity) or 2-hydroxy fatty acid-containing ceramides (HFA-CgalT activity). Although detection of both CgalT activities was possible in all fractions, HFA-CgalT activity was enriched in F1 and F2 fractions, which also showed an enrichment of Golgi and endoplasmic reticulum markers, respectively. It is interesting that NFA-CgalT activity was significantly enriched in the F2 fraction. These results suggest that hydroxylated and nonhydroxylated galactocerebrosides may be synthesized at different intracellular locations.
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D002499:Centrifugation, Density Gradient; D004721:Endoplasmic Reticulum / Q000201:enzymology; D005260:Female; D005700:Galactosyltransferases / Q000378:metabolism*; D051147:Ganglioside Galactosyltransferase; D006056:Golgi Apparatus / Q000201:enzymology; D006880:Hydroxy Acids / Q000378:metabolism; D007124:Immunoenzyme Techniques; D008297:Male; D008854:Microscopy, Electron; D009457:Neuroglia / Q000201:enzymology*; D009836:Oligodendroglia / Q000201:enzymology* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000201:enzymology*
D006880:Hydroxy Acids; D005700:Galactosyltransferases; D051147:Ganglioside Galactosyltransferase