Deficiencies in the endoplasmic reticulum (ER)-membrane protein Gab1p perturb transfer of glycosylphosphatidylinositol to proteins and cause perinuclear ER-associated actin bar formation

Stephen J. Grimme, Xiang Dong Gao, Paul S. Martin, Kim Tu, Serguei E. Tcheperegine, Kathleen Corrado, Anne E. Farewell, Peter Orlean, Erfei Bi

Research output: Contribution to journalArticle

Abstract

The essential GAB1 gene, which encodes an endoplasmic reticulum (ER)-membrane protein, was identified in a screen for mutants defective in cellular morphogenesis. A temperature-sensitive gab1 mutant accumulates complete glycosylphosphatidylinositol (GPI) precursors, and its temperature sensitivity is suppressed differentially by overexpression of different subunits of the GPI transamidase, from strong suppression by Gpi8p and Gpi17p, to weak suppression by Gaa1p, and to no suppression by Gpi16p. In addition, both Gab1p and Gpi17p localize to the ER and are in the same protein complex in vivo. These findings suggest that Gab1p is a subunit of the GPI transamidase with distinct relationships to other subunits in the same complex. We also show that depletion of Gab1p or Gpi8p, but not Gpi17p, Gpi16p, or Gaa1p causes accumulation of cofilin-decorated actin bars that are closely associated with the perinuclear ER, which highlights a functional interaction between the ER network and the actin cytoskeleton.

Original languageEnglish (US)
Pages (from-to)2758-2770
Number of pages13
JournalMolecular biology of the cell
Volume15
Issue number6
DOIs
StatePublished - Jun 1 2004

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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