Caenorhabditis elegans RME-6 is a novel regulator of RAB-5 at the clathrin-coated pit

Nat Cell Biol. 2005 Jun;7(6):559-69. doi: 10.1038/ncb1261. Epub 2005 May 15.

Abstract

Here we identify a new regulator of endocytosis called RME-6. RME-6 is evolutionarily conserved among metazoans and contains Ras-GAP (GTPase-activating protein)-like and Vps9 domains. Consistent with the known catalytic function of Vps9 domains in Rab5 GDP/GTP exchange, we found that RME-6 binds specifically to Caenorhabditis elegans RAB-5 in the GDP-bound conformation, and rme-6 mutants have phenotypes that indicate low RAB-5 activity. However, unlike other Rab5-associated proteins, a rescuing green fluorescent protein (GFP)-RME-6 fusion protein primarily localizes to clathrin-coated pits, physically interacts with alpha-adaptin, a clathrin adaptor protein, and requires clathrin to achieve its cortical localization. In rme-6 mutants, transport from the plasma membrane to endosomes is defective, and small 110-nm endocytic vesicles accumulate just below the plasma membrane. These results suggest a mechanism for the activation of Rab5 in clathrin-coated pits or clathrin-coated vesicles that is essential for the delivery of endocytic cargo to early endosomes.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Protein Complex alpha Subunits / metabolism
  • Animals
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans / ultrastructure
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / isolation & purification
  • Caenorhabditis elegans Proteins / metabolism*
  • Cell Membrane / metabolism*
  • Cell Membrane / ultrastructure
  • Clathrin-Coated Vesicles / metabolism*
  • Clathrin-Coated Vesicles / ultrastructure
  • Endocytosis / physiology*
  • Endosomes / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / isolation & purification
  • Membrane Proteins / metabolism*
  • Microscopy, Electron, Transmission
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Protein Binding / physiology
  • Protein Transport / physiology
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transport Vesicles / metabolism
  • rab5 GTP-Binding Proteins / genetics
  • rab5 GTP-Binding Proteins / metabolism*

Substances

  • Adaptor Protein Complex alpha Subunits
  • Caenorhabditis elegans Proteins
  • Membrane Proteins
  • RME-6 protein, C elegans
  • Recombinant Fusion Proteins
  • rab5 GTP-Binding Proteins

Associated data

  • GENBANK/AY750054