The α-helical region in p24γ2 subunit of p24 protein cargo receptor is pivotal for the recognition and transport of glycosylphosphatidylinositol-anchored proteins

J Biol Chem. 2014 Jun 13;289(24):16835-43. doi: 10.1074/jbc.M114.568311. Epub 2014 Apr 28.

Abstract

Glycosylphosphatidylinositol-anchored proteins (GPI-APs) are group of proteins that depend on p24 cargo receptors for their transport from the endoplasmic reticulum to the Golgi apparatus. The GPI anchor is expected to act as a sorting and transport signal, but so far little is known about the recognition mechanism. In the present study we investigate the GPI-AP transport in cell knockdown of p24γ, the most diverse p24 subfamily. Knockdown of p24γ2 but not of other p24γ family members impaired the transport of a reporter GPI-AP. Restoration of the knockdown-induced phenotype using chimeric constructs between p24γ2 and the related p24γ1 further implied a role of the α-helical region of p24γ2 but not its GOLD domain in the specific binding of GPI-APs. We conclude that motifs in the membrane-adjacent α-helical region of p24γ2 are involved in recognition of GPI-APs and are consequently responsible for the incorporation of these proteins into coat protein complex II-coated transport vesicles.

Keywords: Endoplasmic Reticulum (ER); Glycosylphosphatidylinositol (GPI Anchor); Intracellular Trafficking; Protein Sorting; Protein-Protein Interaction; p24 Proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • CHO Cells
  • Calcium Channels
  • Cricetinae
  • Cricetulus
  • GPI-Linked Proteins / metabolism*
  • Humans
  • Mice
  • Molecular Sequence Data
  • Protein Binding
  • Protein Subunits / chemistry
  • Protein Subunits / genetics
  • Protein Subunits / metabolism
  • Protein Transport
  • TRPV Cation Channels
  • Vesicular Transport Proteins / chemistry
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism*

Substances

  • Calcium Channels
  • GPI-Linked Proteins
  • Protein Subunits
  • TMED5 protein, human
  • TRPV Cation Channels
  • Trpv6 protein, mouse
  • Vesicular Transport Proteins