Raft-like membrane domains contain enzymatic activities involved in the synthesis of mammalian glycosylphosphatidylinositol anchor intermediates.

The synthesis of the glycosylphosphatidylinositol (GPI) anchor occurs in different compartments within the ER. We have previously shown that GPI anchor intermediates including GlcNAc-PI and GlcN-(acyl)PI are present in Triton insoluble membranes (TIMs), believed to be derived from lipid rafts. The present study was initiated to determine if GPI anchor intermediates move to raft-like domains after their synthesis or if these domains represent another ER compartment for GPI anchor synthesis.