Polarized sorting of the copper transporter ATP7B in neurons mediated by recognition of a dileucine signal by AP-1

Mol Biol Cell. 2015 Jan 15;26(2):218-28. doi: 10.1091/mbc.E14-07-1177. Epub 2014 Nov 5.


Neurons are highly polarized cells having distinct somatodendritic and axonal domains. Here we report that polarized sorting of the Cu(2+) transporter ATP7B and the vesicle-SNARE VAMP4 to the somatodendritic domain of rat hippocampal neurons is mediated by recognition of dileucine-based signals in the cytosolic domains of the proteins by the σ1 subunit of the clathrin adaptor AP-1. Under basal Cu(2+) conditions, ATP7B was localized to the trans-Golgi network (TGN) and the plasma membrane of the soma and dendrites but not the axon. Mutation of a dileucine-based signal in ATP7B or overexpression of a dominant-negative σ1 mutant resulted in nonpolarized distribution of ATP7B between the somatodendritic and axonal domains. Furthermore, addition of high Cu(2+) concentrations, previously shown to reduce ATP7B incorporation into AP-1-containing clathrin-coated vesicles, caused loss of TGN localization and somatodendritic polarity of ATP7B. These findings support the notion of AP-1 as an effector of polarized sorting in neurons and suggest that altered polarity of ATP7B in polarized cell types might contribute to abnormal copper metabolism in the MEDNIK syndrome, a neurocutaneous disorder caused by mutations in the σ1A subunit isoform of AP-1.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Adaptor Protein Complex 1 / chemistry
  • Adaptor Protein Complex 1 / genetics
  • Adaptor Protein Complex 1 / metabolism*
  • Adaptor Protein Complex sigma Subunits / chemistry
  • Adaptor Protein Complex sigma Subunits / genetics
  • Adaptor Protein Complex sigma Subunits / metabolism
  • Adenosine Triphosphatases / chemistry
  • Adenosine Triphosphatases / genetics
  • Adenosine Triphosphatases / metabolism*
  • Amino Acid Motifs / genetics
  • Amino Acid Sequence
  • Animals
  • Cation Transport Proteins / chemistry
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Cell Membrane / metabolism
  • Cell Polarity
  • Cells, Cultured
  • Copper / metabolism
  • Copper / pharmacology
  • Copper-Transporting ATPases
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • HeLa Cells
  • Humans
  • Leucine / chemistry
  • Leucine / genetics
  • Leucine / metabolism*
  • Microscopy, Confocal
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Neurons / drug effects
  • Neurons / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Transport / drug effects
  • R-SNARE Proteins / chemistry
  • R-SNARE Proteins / genetics
  • R-SNARE Proteins / metabolism
  • Rats
  • trans-Golgi Network / metabolism


  • Adaptor Protein Complex 1
  • Adaptor Protein Complex sigma Subunits
  • Cation Transport Proteins
  • R-SNARE Proteins
  • VAMP4 protein, rat
  • Green Fluorescent Proteins
  • Copper
  • Adenosine Triphosphatases
  • Atp7b protein, rat
  • Copper-Transporting ATPases
  • Leucine