TFG Promotes Organization of Transitional ER and Efficient Collagen Secretion

Cell Rep. 2016 May 24;15(8):1648-59. doi: 10.1016/j.celrep.2016.04.062. Epub 2016 May 12.


Collagen is the most abundant protein in the animal kingdom. It is of fundamental importance during development for cell differentiation and tissue morphogenesis as well as in pathological processes such as fibrosis and cancer cell migration. However, our understanding of the mechanisms of procollagen secretion remains limited. Here, we show that TFG organizes transitional ER (tER) and ER exit sites (ERESs) into larger structures. Depletion of TFG results in dispersion of tER elements that remain associated with individual ER-Golgi intermediate compartments (ERGICs) as largely functional ERESs. We show that TFG is not required for the transport and packaging of small soluble cargoes but is necessary for the export of procollagen from the ER. Our work therefore suggests a key relationship between the structure and function of ERESs and a central role for TFG in optimizing COPII assembly for procollagen export.

MeSH terms

  • Collagen / metabolism*
  • Endoplasmic Reticulum / metabolism*
  • Golgi Apparatus / metabolism
  • Green Fluorescent Proteins / metabolism
  • Humans
  • Mannosidases / metabolism
  • Models, Biological
  • Protein Transport
  • Proteins / metabolism*
  • RNA, Small Interfering / metabolism
  • Reproducibility of Results


  • Proteins
  • RNA, Small Interfering
  • TFG protein, human
  • Green Fluorescent Proteins
  • Collagen
  • Mannosidases
  • mannosyl-oligosaccharide 1,3 - 1,6-alpha-mannosidase