GLYCOSPHINGOLIPIDS OF A GREEN MONKEY KIDNEY-CELL LINE (GMK AH-1) - EVIDENCE FOR A NOVEL PENTAGLYCOSYLCERAMIDE BASED ON GLOBOTETRAOSYLCERAMIDE

Total non-acid glycolipid fractions were isolated from GMK-AH-1 cells grown in fetal calf serum and in horse serum. For comparison, glycolipids were also prepared from green monkey (C. aethiops) kidney and from fetal calf serum. The major glycolipids from GMK-AH-1 cells grown in fetal calf serum were isolated by silicic acid column chromatography and preparative TLC. These fractions were characterized mainly by TLC, mass spectrometry and gas chromatography. The structures of the glycolipids isolated were proposed as follows: Glc[glucose]1 .fwdarw. 1Cer[ceramide] Gal[galactose]1 .fwdarw. 1Cer, Gal1 .fwdarw. 4Glc1 .fwdarw. 1Cer, Gal1 .fwdarw. 4Gal1 .fwdarw. 4Glc1 .fwdarw. 1Cer, GalNAc[galactosamine]1 .fwdarw. 3Gal1 .fwdarw. 4Gal1 .fwdarw. 4Glc1 .fwdarw. 1Cer. A novel pentaglycosylceramide with the probable structure Gal.beta.1 .fwdarw. 3GalNAc.beta.1 .fwdarw. 3Gal.alpha.1 .fwdarw. 4Gal.beta.1 .fwdarw. 4Glc.beta.1 .fwdarw. 1Cer was also present. The ceramides contained mainly dihydroxy 18:1 long-chain base in combination with non-hydroxy 16:0-24:0 fatty acids. Small amounts of trihydroxy 18:0 long-chain base and hydroxy 22:0-24:0 fatty acids were also present in the mono- and diglycosylceramide fractions. The glycolipid patterns of GMK-AH-1 cells grown in fetal calf serum or horse serum were identical. The pentaglycosylceramide present in the cultured cells could not be detected with certainty in the kidney tissue. The uptake of this glycolipid from the culture medium is unlikely as it seems to be lacking in calf serum.