Characterization of the lipid content ofToxoplasma gondiirhoptries

Abstract
Quantitative and qualitative analysis of lipids has been performed on a rhoptry fraction purified fromToxoplasma gondiitachyzoites. The lipid to protein ratio was estimated to be 0·26. The cholesterol to phospholipid ratio was unusually high at 1·48. Phosphatidylcholine was the major phospholipid; phosphatidylserine, phosphatidylinositol and sphingomyelin were absent whereas significant amounts of phosphatidic acid and lysophospholipids were found. This pelicular composition could be related to functional involvement of the organelle in host-cell invasion.