Differential palmitoylation of the endosomal SNAREs syntaxin 7 and syntaxin 8

J Lipid Res. 2009 Mar;50(3):398-404. doi: 10.1194/jlr.M800360-JLR200. Epub 2008 Oct 31.

Abstract

Palmitoylation is a posttranslational modification that regulates protein trafficking and stability. In this study we investigated whether the endosomal soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNARE) proteins syntaxin 7 and syntaxin 8 are modified with palmitate. Using metabolic labeling and site-directed mutagenesis, we show that human syntaxins 7 and 8 are modified with palmitate through a thioester linkage. Palmitoylation is dependent upon cysteine 239 of human syntaxin 7 and cysteine 214 of syntaxin 8, residues that are located on the cytoplasmic face of the transmembrane domain (TMD). Palmitoylation of syntaxin 8 is minimally affected by the Golgi-disturbing agent brefeldin A (BFA), whereas BFA dramatically inhibits palmitoylation of syntaxin7. The differential effect of BFA suggests that palmitoylation of syntaxins 7 and 8 occurs in distinct subcellular compartments. Palmitoylation does not affect the rate of protein turnover of syntaxins 7 and 8 nor does it influence the steady-state localization of syntaxin 8 in late endosomes. Syntaxin 7 actively cycles between endosomes and the plasma membrane. Palmitoylation-defective syntaxin 7 is selectively retained on the plasma membrane, suggesting that palmitoylation is important for intercompartmental transport of syntaxin 7.

Publication types

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

MeSH terms

  • Brefeldin A / pharmacology
  • Cell Membrane / metabolism
  • DNA, Complementary / genetics
  • Endosomes / metabolism*
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Half-Life
  • HeLa Cells
  • Humans
  • Lipoylation / drug effects
  • Microscopy, Confocal
  • Multiprotein Complexes
  • Mutagenesis, Site-Directed
  • Qa-SNARE Proteins / chemistry*
  • Qa-SNARE Proteins / genetics
  • Qa-SNARE Proteins / metabolism*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transfection

Substances

  • DNA, Complementary
  • Multiprotein Complexes
  • Qa-SNARE Proteins
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • Brefeldin A