Uptake of radiolabeled galactosyl-(alpha1 goes to 4)-galactosyl-(beta1 goes to 4)-glucosylceramide by human serum lipoproteins in vitro.

Human serum was exposed to various amounts of [6-3H] galactosyl-(alpha1 goes to 4)-galactosyl-(beta1 goes to 4)-glucosylceramide under standardized conditions in vitro, and the uptake of the lipid by serum lipoproteins was determined. Of the bound glycolipid, 2% was isolated with very low density, 24% with low density-, 47% with high density lipoproteins and 27% with the ultracentrifugal residue. The distribution was different from the distribution of endogenous galactosyl-galactosylglucosylceramide, indicating that the glycolipid is probably an integral part of the lipoprotein complexes in vivo.