Purification and properties of rat liver globotriaosylceramide synthase, UDP-galactose:lactosylceramide alpha 1-4-galactosyltransferase.

摘要: The enzyme which catalyzes the transfer of galactose from UDP-galactose to lactosylceramide (LacCer) was obtained in a 32,000-fold purified and apparently homogeneous form rat liver by procedure involving affinity chromatography on UDP-hexanolamine-Sepharose LacCer-Sepharose. is composed two nonidentical subunits whose apparent molecular weights are 65,000 22,000. Methylation hydrolysis product formed incubation with [3H]LacCer yielded 2,3,6-tri-O-methyl-[3H]galactose, indicating that residue introduced position C-4 terminal LacCer. also specifically reacted monoclonal antibody directed globotriaosylceramide (Gal alpha 1-4Gal beta 1-4Glc 1-1Cer). This indicates exclusively 1-4-galactosyltransferase. Studies substrate specificity indicate highly specific for synthesis GbOse3Cer clearly distinct enzymes responsible formation iGbOse3Cer 1-3Gal 1-4Glc-Cer) blood group-B substance, possess 1-3 galactosidic linkages at nonreducing termini. 1-4-galactosyltransferase galabiaosylceramide 1-1Cer) IV4Gal-nLacOse4 (P1 antigen). These studies represent first report properties alpha-galactosyltransferase catalyzing sugar residues glycolipids.