C11ORF24 is a novel type I membrane protein that cycles between the Golgi apparatus and the plasma membrane in Rab6-positive vesicles

PLoS One. 2013 Dec 2;8(12):e82223. doi: 10.1371/journal.pone.0082223. eCollection 2013.

Abstract

The Golgi apparatus is an intracellular compartment necessary for post-translational modification, sorting and transport of proteins. It plays a key role in mitotic entry through the Golgi mitotic checkpoint. In order to identify new proteins involved in the Golgi mitotic checkpoint, we combine the results of a knockdown screen for mitotic phenotypes and a localization screen. Using this approach, we identify a new Golgi protein C11ORF24 (NP_071733.1). We show that C11ORF24 has a signal peptide at the N-terminus and a transmembrane domain in the C-terminal region. C11ORF24 is localized on the Golgi apparatus and on the trans-Golgi network. A large part of the protein is present in the lumen of the Golgi apparatus whereas only a short tail extends into the cytosol. This cytosolic tail is well conserved in evolution. By FRAP experiments we show that the dynamics of C11ORF24 in the Golgi membrane are coherent with the presence of a transmembrane domain in the protein. C11ORF24 is not only present on the Golgi apparatus but also cycles to the plasma membrane via endosomes in a pH sensitive manner. Moreover, via video-microscopy studies we show that C11ORF24 is found on transport intermediates and is colocalized with the small GTPase RAB6, a GTPase involved in anterograde transport from the Golgi to the plasma membrane. Knocking down C11ORF24 does not lead to a mitotic phenotype or an intracellular transport defect in our hands. All together, these data suggest that C11ORF24 is present on the Golgi apparatus, transported to the plasma membrane and cycles back through the endosomes by way of RAB6 positive carriers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Cycle / physiology
  • Cell Membrane / metabolism*
  • Golgi Apparatus / metabolism*
  • HeLa Cells
  • Humans
  • Membrane Proteins / metabolism*
  • Protein Processing, Post-Translational / physiology
  • rab GTP-Binding Proteins / metabolism*

Substances

  • C11orf24 protein, human
  • Membrane Proteins
  • Rab6 protein
  • rab GTP-Binding Proteins

Grants and funding

This work has been supported by the Institut Curie and the CNRS. IP and AAH are supported by the EU's Seventh Framework Programme (FP7/2007-2013) under grant agreement 241548 (MitoSys Project), AD was supported by a long term fellowship from HFSP (LT000029/2010-L). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.