= Sphingoglycolipid
= Glycosphingolipid
{synonym}
A \b[sphingoglycolipid], also called a <glycosphingolipid>, is a <glycolipid> whose lipid portion has a sphingoid backbone. A common arrangement is a <carbohydrate> headgroup linked to a <ceramide>, which contains a long-chain amino alcohol and an amide-linked <fatty acid>. The sugar portion and lipid portion can vary independently, so a class name does not usually specify one unique molecular formula.<Nomenclature of Lipids by the IUPAC-IUB Commission on Biochemical Nomenclature>[Lip-3, General Considerations and generic/individual glycolipid names]{ref}
<Glucosylceramide> is a useful example: one <glucose> residue forms the headgroup, while the <ceramide> supplies the hydrophobic portion. Changing the sugar headgroup changes the exposed carbohydrate structure; changing the <fatty acid> chain changes the lipid portion. Two samples described as glucosylceramide can therefore differ in their detailed chain composition.<Nomenclature of Lipids by the IUPAC-IUB Commission on Biochemical Nomenclature>[Lip-3: glucosylceramide example and heterogeneity of fatty acids/long-chain bases]{ref}
These molecules are also experimentally useful markers. The1990 study proposing <Sphingomonas> combined cellular sphingoglycolipid observations with <16S ribosomal RNA> comparisons and <ubiquinone> composition. Agreement between chemical and sequence observations supported the taxonomic proposal; a lipid measurement was one part of the evidence, rather than a substitute for all other comparisons.<Sphingomonas genus and species proposals by E. Yabuuchi and others>[Primary Abstract: three lines of evidence for the proposed genus]{ref}
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