Gpi1, a Saccharomyces cerevisiae protein that participates in the first step in glycosylphosphatidylinositol anchor synthesis.
The temperature-sensitive Saccharomyces cerevisiae gpi1 mutant is blocked in [3H]inositol incorporation into protein and defective in the synthesis of N-acetylglucosaminylphosphatidylinositol, the first step in glycosylphosphatidylinositol (GPI) anchor assembly (Leidich, S. D., Drapp, D. A., and Orlean, P. (1994) J. Biol. Chem. 269, 10193-10196). The GPI1 gene, which encodes a 609-amino acid membrane protein, was cloned by complementation of the temperature sensitivity of gpi1 and corrects the mutant's [3H]inositol labeling and enzymatic defects. Disruption of GPI1 yields viable haploid cells that are temperature-sensitive for growth, for [3H]inositol incorporation into protein, and for GPI anchor-dependent processing of the Gas1/Ggp1 protein and that lack in vitro N-acetylglucosaminylphosphatidylinositol synthetic activity. The Gpi1 protein thus participates in GPI synthesis and is required for growth at 37 degrees C. When grown at a semipermissive temperature of 30 degrees C, gpi1 cells and gpi1::URA3 disruptants form large, round, multiply budded cells with a separation defect. Homozygous gpi1/gpi1, gpi1::URA3/gpi1::URA3, gpi2/gpi2, and gpi3/gpi3 diploids undergo meiosis, but are defective in ascospore wall maturation for they fail to give the fluorescence due to the dityrosine-containing layer in the ascospore wall. These findings indicate that GPIs have key roles in the morphogenesis and development of S. cerevisiae.
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. p-orlean@uiuc.edu
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002240:Carbohydrate Sequence; D003001:Cloning, Molecular; D005800:Genes, Fungal; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis*; D006720:Homozygote; D007294:Inositol / Q000378:metabolism; D007700:Kinetics; D008565:Membrane Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013172:Spores, Fungal; D013696:Temperature
C102317:GPI1 protein, S cerevisiae; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D007294:Inositol