ABSTRACT
A novel group of glycosphingolipids was identified in the nervous tissue and skin of the mollusc, Aplysia kurodai, which lacks gangliosides. More than 30 glycolipids were detected on HPTLC plates and the structures of 9 major glycolipids were determined. They were pentaosylglycosphingolipids and their common core structure was GalNAcα1â3Galß1â4Glcß1â1ceramide, except for one glycolipid in which Galß of the core structure was replaced by Galα. 3-O-MeGalß or 4-O-MeGlcNAcα or 3,4-O-carboxyethylideneGalß was at their non-reducing ends. Galα or Fucα binds to Gal of the core structure at 2C as a side chain sugar. One to three 2-aminoethylphosphonic acids and/or phosphoethanolamine link to the glycolipids. Immunohistochemically, glycolipids having carboxyethylideneGal at their non-reducing ends were localized exclusively in nerve bundles. Glycolipids activated cAMP-dependent protein kinase in the rat brain and may directly activate cAMP-dependent protein kinase in a manner similar, but not identical, to that of cAMP. The biological functions of glycolipids may share neurobiological functions proposed for gangliosides in vertebrates.
