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Ynl038wp (Gpi15p) is the Saccharomyces cerevisiae homologue of human Pig‐Hp and participates in the first step in glycosylphosphatidylinositol assembly
Author(s) -
Yan Benjamin C.,
Westfall Barbara A.,
Orlean Peter
Publication year - 2001
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.783
Subject(s) - biology , saccharomyces cerevisiae , mutant , candida albicans , biochemistry , biosynthesis , gene , protein subunit , microbiology and biotechnology , phosphatidylinositol , phosphorylation , genetics
Abstract Glycosylphosphatidylinositols (GPIs) are found in all eukaryotes and are synthesized in a pathway that starts with the transfer of N‐ acetylglucosamine (GlcNAc) from UDP‐GlcNAc to phosphatidylinositol (PI). This reaction is carried out by a protein complex, three of whose subunits in humans, hGpi1p, Pig‐Cp and Pig‐Ap, have sequence and functional homologues in the Saccharomyces cerevisiae Gpi1, Gpi2 and Gpi3 proteins, respectively. Human GlcNAc‐PI synthase contains two further subunits, Pig‐Hp and PigPp. We report that the essential YNL038w gene encodes the S. cerevisiae homologue of Pig‐Hp. Haploid YNL038w ‐deletion strains were created, in which Ynl038wp could be depleted by repressing YNL038w expression using the GAL10 promoter. Depletion of Ynl038wp from membranes virtually abolished in vitro GlcNAc‐PI synthetic activity, indicating that Ynl038wp is necessary for GlcNAc‐PI synthesis in vitro . Further, depletion of Ynl038wp in an smp3 mutant background prevented the formation of the trimannosylated GPI intermediates that normally accumulate in this late‐stage GPI assembly mutant. Ynl038wp is therefore required for GPI synthesis in vivo . Because YNL038w encodes a protein involved in GPI biosynthesis, we designate the gene GPI15 . Potential Pig‐Hp/Gpi15p counterparts are also encoded in the genomes of Schizosacchomyces pombe and Candida albicans . Copyright © 2001 John Wiley & Sons, Ltd.