Identification and characterization of TMEM33 as a reticulon-binding protein

Kobe J Med Sci. 2014 Nov 6;60(3):E57-65.


Endoplasmic reticulum (ER) is an organelle that has an elaborate and continuous membrane system composed of sheet-like cisternae and a network of interconnected tubules. The ER tubules are shaped by reticulons, a conserved ER membrane protein family. However, how the membrane-shaping activity is regulated remains to be elucidated. To understand the mode of action of reticulons, we isolated TMEM33, a conserved protein harboring three transmembrane domains, as a reticulon 4C-binding protein by affinity chromatography. In addition to reticulon 4C, TMEM33 binds to reticulon 1A, -2B, -3C and a reticulon homology domain-containing protein Arl6IP1. Exogenously expressed TMEM33 localizes at both the ER membrane and the nuclear envelope. Exogenously expressed TMEM33 co-localizes with exogenously expressed reticulon 4C well at the ER sheets and partially at the ER tubules. Exogenously expressed TMEM33 suppresses the exogenously expressed reticulon 4C-induced tubulation of ER. These results suggest that TMEM33 has a potency to suppress the membrane-shaping activity of reticulons, thereby regulating the tubular structure of ER.

Keywords: ER tubules; Reticulon; TMEM33.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain Chemistry
  • Carrier Proteins / analysis*
  • Carrier Proteins / metabolism
  • Chromatography, Affinity
  • Cloning, Molecular
  • Endoplasmic Reticulum / chemistry
  • Gene Expression
  • HeLa Cells
  • Humans
  • Immunosorbent Techniques
  • Membrane Proteins / analysis*
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Myelin Proteins / genetics
  • Myelin Proteins / metabolism*
  • Myelin Proteins / physiology
  • Nogo Proteins
  • Nuclear Envelope / chemistry
  • Recombinant Fusion Proteins
  • Swine
  • Transfection


  • Carrier Proteins
  • Membrane Proteins
  • Myelin Proteins
  • Nogo Proteins
  • RTN4 protein, human
  • Recombinant Fusion Proteins
  • transmembrane protein 33, human