Glycosyl inositolphospholipid-anchored structures in Herpetomonas davidi

Glycosyl inositolphospholipid (GPI)-anchored structures in the monogenetic parasite Herpetomonas davidi, were labeled with [ 3H]myristic acid and [ 3H]glucosamine, and characterized by enzymatic and chemical treatments that are typical for the identification of GPI anchors. [ 3H]Myristate incorporated into two different pools of GPI-linked structures that could be separated by chromatography on octyl-Sepharose. One pool consisted of three GPI-anchored proteins with apparent molecular masses of 21, 31 and 45 kDa, and the GPI lipid moieties were identified as alkyl- lyso-glycerols. The label in the other pool associated with lipopeptidophosphoglycan (LPPG)-like structures of approximately 12-kDa molecular mass, containing ceramide-type GPI lipid anchors. While protein GPI anchors could also be labeled using [ 3H]glucosamine as radiolabeled GPI anchor precursor, hardly any radioactivity was incorporated into the LPPG-like structures. H. davidi is one of the few organisms identified to date that synthesizes two structurally different lipid moieties for GPI anchoring of membrane components.