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The N-terminal peptide of the syntaxin Tlg2p modulates binding of its closed conformation to Vps45p.

The Sec1/Munc18 (SM) protein family regulates intracellular trafficking through interactions with individual SNARE proteins and assembled SNARE complexes. Revealing a common mechanism of this regulation has been challenging, largely because of the multiple modes of interaction observed between SM proteins and their cognate syntaxin-type SNAREs. These modes include binding of the SM to a closed conformation of syntaxin, binding to the N-terminal peptide of syntaxin, binding to assembled SNARE complexes, and/or binding to nonsyntaxin SNAREs. The SM protein Vps45p, which regulates endosomal trafficking in yeast, binds the conserved N-terminal peptide of the syntaxin Tlg2p. We used size exclusion chromatography and a quantitative fluorescent gel mobility shift assay to reveal an additional binding site that does not require the Tlg2p N-peptide. Characterization of Tlg2p mutants and truncations indicate that this binding site corresponds to a closed conformation of Tlg2p. Furthermore, the Tlg2p N-peptide competes with the closed conformation for binding, suggesting a fundamental regulatory mechanism for SM-syntaxin interactions in SNARE assembly and membrane fusion.

Pubmed ID: 19667197


  • Furgason ML
  • MacDonald C
  • Shanks SG
  • Ryder SP
  • Bryant NJ
  • Munson M


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

August 25, 2009

Associated Grants

  • Agency: Biotechnology and Biological Sciences Research Council, Id: 17/C19548
  • Agency: Biotechnology and Biological Sciences Research Council, Id: C19548
  • Agency: NIGMS NIH HHS, Id: GM068803
  • Agency: NIGMS NIH HHS, Id: GM081422
  • Agency: NIGMS NIH HHS, Id: R01 GM081422

Mesh Terms

  • Binding, Competitive
  • Circular Dichroism
  • Electrophoretic Mobility Shift Assay
  • Immunoblotting
  • Kinetics
  • Models, Molecular
  • Mutation
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • Qa-SNARE Proteins
  • Recombinant Proteins
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Vesicular Transport Proteins