Catalyzes the transfer of galactose from UDP-alpha-D-galactose to lactosylceramide/beta-D-galactosyl-(1->4)-beta-D-glucosyl-(1<->1)-ceramide(d18:1(4E)) to produce globotriaosylceramide/globoside Gb3Cer (d18:1(4E)) . Also able to transfer galactose to galactosylceramide/beta-D-Gal-(1<->1')-Cer . Globoside Gb3Cer is a glycosphingolipid of the globo serie, one of the major types of neutral root structures of glycosphingolipids, that constitute a significant portion of mammalian cell membranes (Probable). Globotriaosylceramide/globoside Gb3Cer in blood and tissue cell membranes is the antigen Pk of blood histogroup P .
(Microbial infection) Globotriaosylceramide is one of the cellular ligands for bacterial verotoxins.
Subcellular locations: Golgi apparatus membrane
Ubiquitous. Highly expressed in kidney, heart, spleen, liver, testis and placenta.