Two different types of lipid moieties are present in glycophosphoinositol-anchored membrane proteins of Saccharomyces cerevisiae.
Numerous glycoproteins of Saccharomyces cerevisiae are anchored in the lipid bilayer by a glycophosphatidylinositol (GPI) anchor. Mild alkaline hydrolysis reveals that the lipid components of these anchors are heterogeneous in that both base-sensitive and base-resistant lipid moieties can be found on most proteins. The relative abundance of base-resistant lipid moieties is different for different proteins. Strong alkaline or acid hydrolysis of the mild base-resistant lipid component liberates C18-phytosphingosine indicating the presence of a ceramide. Two lines of evidence suggest that proteins are first attached to a base-sensitive GPI anchor, the lipid moiety of which subsequently gets exchanged for a base-resistant ceramide: (i) an early glycolipid intermediate of GPI biosynthesis only contains base-sensitive lipid moieties; (ii) after a pulse with [3H]myo-inositol the relative abundance of base-sensitive GPI anchors decreases significantly during chase. This decrease does not take place if GPI-anchored proteins are retained in the ER.
Conzelmann
A
A
Institute of Biochemistry, University of Lausanne, Epalinges, Switzerland.
Puoti
A
A
Lester
R L
RL
Desponds
C
C
D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D006017:Glycolipids / Q000032:analysis / Q000378:metabolism*; D017261:Glycosylphosphatidylinositols; D007294:Inositol / Q000378:metabolism; D007700:Kinetics; D008051:Lipid Bilayers; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D008970:Molecular Weight; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D010716:Phosphatidylinositols / Q000032:analysis / Q000378:metabolism*; D011865:Radioisotope Dilution Technique; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014316:Tritium
D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D008051:Lipid Bilayers; D008565:Membrane Proteins; D010169:Palmitic Acids; D010716:Phosphatidylinositols; D014316:Tritium; D019308:Palmitic Acid; D007294:Inositol