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Gaa1p and Gpi8p Are Components of a Glycosylphosphatidylinositol (GPI) Transamidase That Mediates Attachment of GPI to Proteins
Journal article

Gaa1p and Gpi8p Are Components of a Glycosylphosphatidylinositol (GPI) Transamidase That Mediates Attachment of GPI to Proteins

  • Ohishi, Kazuhito Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; and
  • Inoue, Norimitsu Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; and
  • Maeda, Yusuke Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; and
  • Takeda, Junji Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; and
  • Riezman, Howard Biozentrum, University of Basel, Basel CH-4056, Switzerland
  • Kinoshita, Taroh Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan; and
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Published in:
  • Molecular Biology of the Cell. - American Society for Cell Biology (ASCB). - 2000, vol. 11, no. 5, p. 1523-1533
Cell Biology
Molecular Biology
English Many eukaryotic cell surface proteins are anchored to the membrane via glycosylphosphatidylinositol (GPI). The GPI is attached to proteins that have a GPI attachment signal peptide at the carboxyl terminus. The GPI attachment signal peptide is replaced by a preassembled GPI in the endoplasmic reticulum by a transamidation reaction through the formation of a carbonyl intermediate. GPI transamidase is a key enzyme of this posttranslational modification. Here we report that Gaa1p and Gpi8p are components of a GPI transamidase. To determine a role of Gaa1p we disrupted aGAA1/GPAA1 gene in mouse F9 cells by homologous recombination. GAA1 knockout cells were defective in the formation of carbonyl intermediates between precursor proteins and transamidase as determined by an in vitro GPI-anchoring assay. We also show that cysteine and histidine residues of Gpi8p, which are conserved in members of a cysteine protease family, are essential for generation of a carbonyl intermediate. This result suggests that Gpi8p is a catalytic component that cleaves the GPI attachment signal peptide. Moreover, Gaa1p and Gpi8p are associated with each other. Therefore, Gaa1p and Gpi8p constitute a GPI transamidase and cooperate in generating a carbonyl intermediate, a prerequisite for GPI attachment.
Language
  • English
Open access status
green
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Persistent URL
https://sonar.ch/global/documents/92638
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