The  β subunit of the Sec61p endoplasmic reticulum translocon interacts with the exocyst complex in Saccharomyces cerevisiae

Jaana Toikkanen, Juha Miller, Hans Söderlund, Jussi Jäntti (Corresponding Author), Sirkka Keränen (Corresponding Author)

Research output: Contribution to journalArticleScientificpeer-review

65 Citations (Scopus)

Abstract

The exocyst is a conserved protein complex proposed to mediate vesicle tethering at the plasma membrane. Previously, we identified SEB1/SBH1, encoding the β subunit of the Sec61p ER translocation complex, as a multicopy suppressor of the sec15-1 mutant, defective for one subunit of the exocyst complex. Here we show the functional and physical interaction between components of endoplasmic reticulum translocon and the exocytosis machinery. We show that overexpression of SEB1 suppresses the growth defect in all exocyst sec mutants. In addition, overexpression of SEC61 or SSS1 encoding the other two components of the Sec61p complex suppressed the growth defects of several exocyst mutants. Seb1p was coimmunoprecipitated from yeast cell lysates with Sec15p and Sec8p, components of the exocyst complex, and with Sec4p, a secretory vesicle associated Rab GTPase that binds to Sec15p and is essential for exocytosis. The interaction between Seb1p and Sec15p was abolished in sec15-1 mutant and was restored upon SEB1 overexpression. Furthermore, in wild type cells overexpression of SEB1 as well as SEC4 resulted in increased production of secreted proteins. These findings propose a novel functional and physical link between the endoplasmic reticulum translocation complex and the exocyst.
Original languageEnglish
Pages (from-to)20946-20953
Number of pages8
JournalJournal of Biological Chemistry
Volume278
Issue number23
DOIs
Publication statusPublished - 2003
MoE publication typeA1 Journal article-refereed

Keywords

  • exocyst
  • exocyst complexes
  • endoplasmic reticulum

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