An isoform of the Golgi t-SNARE, syntaxin 5, with an endoplasmic reticulum retrieval signal

Mol Biol Cell. 1997 Sep;8(9):1777-87. doi: 10.1091/mbc.8.9.1777.

Abstract

The early Golgi t-SNARE (target-membrane-associated soluble-N-ethylmaleimide-sensitive factor attachment protein receptor) syntaxin 5 is thought to specify the docking site for both COPI and COPII coated vesicles originating from the endoplasmic reticulum (ER) and COPI vesicles on the retrograde pathway. We now show that there are two forms of syntaxin 5 that appear to be generated from the same mRNA by alternative initiation of translation. The short form (35 kDa) corresponds to the published sequence. The long form (42 kDa) has an N-terminal cytoplasmic extension containing a predicted type II ER retrieval signal. When grafted onto a reporter molecule, this signal localized the construct to the ER. Biochemical fractionation and immunofluorescence microscopy showed that there was less of the long form in the Golgi apparatus and more in peripheral punctate structures, some of which colocalized with markers of the intermediate compartment. The predicted absence of the long form in budding yeast points to a function unique to higher organisms.

MeSH terms

  • Alternative Splicing
  • Amino Acid Sequence
  • Animals
  • Endoplasmic Reticulum / physiology*
  • Golgi Apparatus / chemistry*
  • Golgi Apparatus / metabolism
  • Golgi Apparatus / physiology
  • Humans
  • Isomerism
  • Liver / chemistry
  • Membrane Proteins / chemistry*
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology
  • Molecular Sequence Data
  • Molecular Weight
  • Qa-SNARE Proteins
  • Rats
  • Rats, Sprague-Dawley
  • SNARE Proteins
  • Signal Transduction*
  • Vesicular Transport Proteins*

Substances

  • Membrane Proteins
  • Qa-SNARE Proteins
  • SNARE Proteins
  • Vesicular Transport Proteins

Associated data

  • GENBANK/U87971