High-curvature domains of the ER are important for the organization of ER exit sites in Saccharomyces cerevisiae

J Cell Sci. 2012 Jul 15;125(Pt 14):3412-20. doi: 10.1242/jcs.100065. Epub 2012 Mar 30.

Abstract

Protein export from the endoplasmic reticulum (ER) to the Golgi apparatus occurs at specialized regions known as the ER exit sites (ERES). In Saccharomyces cerevisiae, ERES appear as numerous scattered puncta throughout the ER. We examined ERES within the peripheral ER, finding that the proteins comprising the ERES localize on high-curvature ER domains where curvature-stabilizing protein Rtn1 is present. Δrtn1 Δrtn2 Δyop1 cells have fewer high-curvature ER domains, but ERES accumulate at the remaining high-curvature ER domains on the edge of expanded ER sheets. We propose that membrane curvature is a key geometric feature for the regulation of ERES localization. We also investigated a spatial relationship between ERES and Golgi cisternae. Golgi cisternae in S. cerevisiae are unstacked, dispersed, and moving in the cytoplasm with cis-cisternae positioned adjacent to ERES, whereas trans-cisternae are not. Morphological changes in the ER of Δrtn1 Δrtn2 Δyop1 cells resulted in aberrant Golgi structures, including cis- and trans-markers, and there was reduced movement at ERES between expanded ER sheets and the plasma membrane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • COP-Coated Vesicles / metabolism
  • Endoplasmic Reticulum / metabolism*
  • Endoplasmic Reticulum / ultrastructure*
  • Golgi Apparatus / metabolism*
  • Intracellular Membranes / metabolism
  • Intracellular Membranes / ultrastructure
  • Membrane Proteins / metabolism
  • Microscopy, Fluorescence
  • Protein Transport
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / ultrastructure*
  • Saccharomyces cerevisiae Proteins / metabolism

Substances

  • Membrane Proteins
  • SEC16 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins