The major surface antigen, P30, of Toxoplasma gondii is anchored by a glycolipid.
P30, the major surface antigen of the parasitic protozoan Toxoplasma gondii, can be specifically labeled with [3H]palmitic acid and with myo-[2-3H]inositol. The fatty acid label can be released by treatment of P30 with phosphatidylinositol-specific phospholipase C (PI-PLC). Such treatment exposes an immunological "cross-reacting determinant" first described on Trypanosoma brucei variant surface glycoprotein. PI-PLC cleavage of intact parasites metabolically labeled with [35S]methionine results in the release of intact P30 polypeptide in a form which migrates faster in polyacrylamide gel electrophoresis. These results argue that P30 is anchored by a glycolipid. Results from thin layer chromatography analysis of purified [3H] palmitate-labeled P30 treated with PI-PLC, together with susceptibility to mild alkali hydrolysis and to cleavage with phospholipase A2, suggest that the glycolipid anchor of T. gondii P30 includes a 1,2-diacylglycerol moiety.
Nagel
S D
SD
Department of Microbiology and Immunology, Stanford University School of Medicine, California 94305.
Boothroyd
J C
JC
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000096:biosynthesis / Q000302:isolation & purification*; D006017:Glycolipids / Q000096:biosynthesis / Q000302:isolation & purification*; D007294:Inositol / Q000378:metabolism; D008715:Methionine / Q000378:metabolism; D008969:Molecular Sequence Data; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D013462:Sulfur Radioisotopes; D014122:Toxoplasma / Q000276:immunology*; D010738:Type C Phospholipases
D000953:Antigens, Protozoan; D006017:Glycolipids; D010169:Palmitic Acids; D013462:Sulfur Radioisotopes; D019308:Palmitic Acid; D007294:Inositol; D008715:Methionine; D010738:Type C Phospholipases