Biochemical Journal

Research article

Saccharomyces cerevisiae GPI10, the functional homologue of human PIG-B, is required for glycosylphosphatidylinositol-anchor synthesis

Christine SÜTTERLIN, M. Victoria ESCRIBANO, Peter GEROLD, Yusuke MAEDA, Maria J. MAZON, Taroh KINOSHITA, Ralph T. SCHWARZ, Howard RIEZMAN


An increasing number of plasma membrane proteins have been shown to be attached to the membrane via a glycosylphosphatidylinositol (GPI) moiety. All eukaryotes share a highly conserved GPI-core structure EthN-P-Man3-GlcN-PI, where EthN is ethanolamine. We have identified a protein encoded by the yeast open reading frame YGL142C that shares 33% identity with the human Pig-B protein. Deletion of this essential gene leads to a block in GPI anchor biosynthesis. We therefore named the gene GPI10. Gpi10p and Pig-B are functional homologues and the lethal deletion of GPI10 can be rescued by expression of the PIG-BcDNA. As found for PIG-B mutant cells, gpi10 deletant cells cannot attach the third mannose in an α-1,2 linkage to the GPI core-structure intermediate. Overexpression of GPI10 gives partial resistance to the GPI-synthesis inhibitor YW3548, suggesting that this gene product may affect the target of the inhibitor.