title: Distinct protein domains are responsible for the interaction of Hrs-2 with SNAP-25. The role of Hrs-2 in 7 S complex formation.
abstract: Regulated secretion of neurotransmitter at the synapse is likely to be mediated by dynamic protein interactions involving components of the vesicle (vesicle-associated membrane protein; VAMP) and plasma membrane (syntaxin and synaptosomal associated protein of 25 kDa (SNAP-25)) along with additional molecules that allow for the regulation of this process. Recombinant Hrs-2 interacts with SNAP-25 in a calcium-dependent manner (they dissociate at elevated calcium levels) and inhibits neurotransmitter release. Thus, Hrs-2 has been hypothesized to serve a negative regulatory role in secretion through its interaction with SNAP-25. In this report, we show that Hrs-2 and SNAP-25 interact directly through specific coiled-coil domains in each protein. The presence of syntaxin enhances the binding of Hrs-2 to SNAP-25. Moreover, while both Hrs-2 and VAMP can separately bind to SNAP-25, they cannot bind simultaneously. Additionally, the presence of Hrs-2 reduces the incorporation of VAMP into the syntaxin.SNAP-25.VAMP (7 S) complex. These findings suggest that Hrs-2 may modulate exocytosis by regulating the assembly of a protein complex implicated in membrane fusion.
authors.affiliation: Department of Neurobiology, W.M. Keck Center for the Neurobiology of Learning and Memory, Houston, Texas 77030, USA.
authors.forename: S
authors.initials: S
authors.lastname: Tsujimoto
authors.forename: A J
authors.initials: AJ
authors.lastname: Bean
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport; D004926:Escherichia coli / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins; D010957:Plasmids; D011485:Protein Binding; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25
chemical_list: D056827:Endosomal Sorting Complexes Required for Transport; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D050765:Qa-SNARE Proteins; D050683:R-SNARE Proteins; D011993:Recombinant Fusion Proteins; D050825:Synaptosomal-Associated Protein 25; D005982:Glutathione Transferase; D000251:Adenosine Triphosphatases; C115505:Hgs protein, rat