Sec16 defines endoplasmic reticulum exit sites and is required for secretory cargo export in mammalian cells

Traffic. 2006 Dec;7(12):1678-87. doi: 10.1111/j.1600-0854.2006.00493.x. Epub 2006 Sep 27.


The selective export of proteins and lipids from the endoplasmic reticulum (ER) is mediated by the coat protein complex II (COPII) that assembles onto the ER membrane. In higher eukaryotes, COPII proteins assemble at discrete sites on the membrane known as ER exit sites (ERES). Here, we identify Sec16 as the protein that defines ERES in mammalian cells. Sec16 localizes to ERES independent of Sec23/24 and Sec13/31. Overexpression, and to a lesser extent, small interfering RNA depletion of Sec16, both inhibit ER-to-Golgi transport suggesting that Sec16 is required in stoichiometric amounts. Sar1 activity is required to maintain the localization of Sec16 at discrete locations on the ER membrane, probably through preventing its dissociation. Our data suggest that Sar1-GTP-dependent assembly of Sec16 on the ER membrane forms an organized scaffold defining an ERES.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cell Membrane / metabolism
  • Endoplasmic Reticulum / metabolism*
  • Gene Expression
  • Golgi Apparatus / metabolism
  • Humans
  • Monomeric GTP-Binding Proteins / genetics
  • Monomeric GTP-Binding Proteins / metabolism
  • Protein Binding
  • Protein Transport
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*


  • SEC16A protein, human
  • Vesicular Transport Proteins
  • Monomeric GTP-Binding Proteins