Trafficking of the vesicular acetylcholine transporter in SN56 cells: a dynamin-sensitive step and interaction with the AP-2 adaptor complex

J Neurochem. 2002 Sep;82(5):1221-8. doi: 10.1046/j.1471-4159.2002.01068.x.

Abstract

The pathways by which synaptic vesicle proteins reach their destination are not completely defined. Here we investigated the traffic of a green fluorescent protein (GFP)-tagged version of the vesicular acetylcholine transporter (VAChT) in cholinergic SN56 cells, a model system for neuronal processing of this cargo. GFP-VAChT accumulates in small vesicular compartments in varicosities, but perturbation of endocytosis with a dominant negative mutant of dynamin I-K44A impaired GFP-VAChT trafficking to these processes. The protein in this condition accumulated in the cell body plasma membrane and in large vesicular patches therein. A VAChT endocytic mutant (L485A/L486A) was also located at the plasma membrane, however, the protein was not sorted to dynamin I-K44A generated vesicles. A fusion protein containing the VAChT C-terminal tail precipitated the AP-2 adaptor protein complex from rat brain, suggesting that VAChT directly interacts with the endocytic complex. In addition, yeast two hybrid experiments indicated that the C-terminal tail of VAChT interacts with the micro subunit of AP-2 in a di-leucine (L485A/L486A) dependent fashion. These observations suggest that the di-leucine motif regulates sorting of VAChT from the soma plasma membrane through a clathrin dependent mechanism prior to the targeting of the transporter to varicosities.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Vesicular Transport
  • Amino Acid Motifs / physiology
  • Amino Acid Substitution
  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Line
  • Dynamin I
  • Dynamins
  • Endocytosis / drug effects
  • Endocytosis / physiology
  • GTP Phosphohydrolases / genetics
  • GTP Phosphohydrolases / metabolism*
  • GTP Phosphohydrolases / pharmacology
  • Genes, Dominant
  • Green Fluorescent Proteins
  • Luminescent Proteins / genetics
  • Macromolecular Substances
  • Membrane Proteins / metabolism*
  • Membrane Transport Proteins*
  • Mice
  • Neurons / cytology
  • Neurons / metabolism*
  • Protein Binding / physiology
  • Protein Transport / physiology
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transfection
  • Two-Hybrid System Techniques
  • Vesicular Acetylcholine Transport Proteins
  • Vesicular Transport Proteins*

Substances

  • Adaptor Proteins, Vesicular Transport
  • Carrier Proteins
  • Luminescent Proteins
  • Macromolecular Substances
  • Membrane Proteins
  • Membrane Transport Proteins
  • Recombinant Fusion Proteins
  • Slc18a3 protein, mouse
  • Slc18a3 protein, rat
  • Vesicular Acetylcholine Transport Proteins
  • Vesicular Transport Proteins
  • Green Fluorescent Proteins
  • Dynamin I
  • GTP Phosphohydrolases
  • Dynamins