A dileucine-like sorting signal directs transport into an AP-3-dependent, clathrin-independent pathway to the yeast vacuole

EMBO J. 1998 May 1;17(9):2482-93. doi: 10.1093/emboj/17.9.2482.

Abstract

Transport of yeast alkaline phosphatase (ALP) to the vacuole depends on the clathrin adaptor-like complex AP-3, but does not depend on proteins necessary for transport through pre-vacuolar endosomes. We have identified ALP sequences that direct sorting into the AP-3-dependent pathway using chimeric proteins containing residues from the ALP cytoplasmic domain fused to sequences from a Golgi-localized membrane protein, guanosine diphosphatase (GDPase). The full-length ALP cytoplasmic domain, or ALP amino acids 1-16 separated from the transmembrane domain by a spacer, directed GDPase chimeric proteins from the Golgi complex to the vacuole via the AP-3 pathway. Mutation of residues Leu13 and Val14 within the ALP cytoplasmic domain prevented AP-3-dependent vacuolar transport of both chimeric proteins and full-length ALP. This Leucine-Valine (LV)-based sorting signal targeted chimeric proteins and native ALP to the vacuole in cells lacking clathrin function. These results identify an LV-based sorting signal in the ALP cytoplasmic domain that directs transport into a clathrin-independent, AP-3-dependent pathway to the vacuole. The similarity of the ALP sorting signal to mammalian dileucine sorting motifs, and the evolutionary conservation of AP-3 subunits, suggests that dileucine-like signals constitute a core element for AP-3-dependent transport to lysosomal compartments in all eukaryotic cells.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adaptor Protein Complex 3
  • Alkaline Phosphatase / chemistry
  • Alkaline Phosphatase / metabolism*
  • Amino Acid Sequence
  • Clathrin / metabolism*
  • DNA-Binding Proteins / metabolism*
  • Genotype
  • Golgi Apparatus / metabolism*
  • Intracellular Membranes / metabolism
  • Leucine*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Pyrophosphatases / chemistry
  • Pyrophosphatases / metabolism
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Sequence Alignment
  • Signal Transduction
  • Transcription Factors / metabolism*
  • Vacuoles / metabolism*
  • Valine

Substances

  • Adaptor Protein Complex 3
  • Clathrin
  • DNA-Binding Proteins
  • Recombinant Fusion Proteins
  • Transcription Factors
  • Alkaline Phosphatase
  • Pyrophosphatases
  • guanosine-diphosphatase
  • Leucine
  • Valine