= Ceramide glucosyltransferase
\b[Ceramide glucosyltransferase], EC2.4.1.80, is a <glycosyltransferase> that transfers a glucose-derived group from <UDP-glucose> to a <ceramide> acceptor, producing <glucosylceramide> and <uridine diphosphate>. The accepted reference reaction specifically names an N-acylsphingosine acceptor and a D-glucosyl-N-acylsphingosine product.<Enzyme Nomenclature by the IUBMB>[EC2.4.1.80, Accepted name and Reaction]{ref}
The transfer changes the lipid headgroup while retaining the ceramide portion. The reaction therefore differs from simply mixing free <glucose> with a lipid, and from transferring an intact nucleotide onto the lipid. The <uridine diphosphate> moiety leaves while the glucose-derived residue remains attached through a <glycosidic bond>.
For a stoichiometric example, suppose a defined mixture begins with12nanomoles of <UDP-glucose> and5nanomoles of the accepted <ceramide>, with no replenishment or side reactions. One glucose-transfer event consumes one donor and one acceptor, so product formation is bounded above by5nanomoles, even though donor remains. This upper bound does not assert complete conversion or determine a reaction rate.
A conceptual activity assay must identify the glucosylated lipid and compare an appropriate enzyme-free control: disappearance of donor alone could reflect another reaction. The IUBMB record also lists other possible acceptors and donors, reminding us that an accepted reference reaction is not a claim of absolute specificity for every preparation.<Enzyme Nomenclature by the IUBMB>[EC2.4.1.80, Comments: sphingosine/dihydrosphingosine acceptors and CDP-glucose donor]{ref}
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