Interaction between the SNARE complex and transmembrane AMPA receptor regulatory protein γ-8 in the rat hippocampus

Objective: Transmembrane AMPA receptor regulatory proteins (TARPs) interact with AMPA receptors and modulate both their trafficking and ion channel properties. The purpose of this study was to identify proteins involved in AMPA receptor trafficking by screening for proteins associated with TARP γ-8. Methods: Rat hippocampal P2 lysates were subjected to immunoprecipitation with an anti-γ-8 antibody, followed by mass spectrometry and immunoblot analysis. Interactions between γ-8 and soluble NSF attachment protein receptor (SNARE) proteins were confirmed by co-immunoprecipitation analysis. Results: Two anti-γ-8 antibodies against synthetic peptides corresponding to amino acids 70-84 and 358-372 co-immunoprecipitated the SNARE protein complex, which included syntaxin-1, SNAP-25, and VAMP-2, from hippocampal P2 lysates. TARP γ-8 interacted with syntaxin-1, but not SNAP-25 and VAMP-2, and other TARP family members also co-immunoprecipitated with syntaxin-1. TARP γ-8 co-localized extensively with syntaxin-1 in transfected COS-7 cells. Conclusion: Our results suggest that γ-8 interacts with syntaxin-1. The interaction between TARPs and syntaxin-1 may have important implications for the assembly and localization of TARP/AMPA receptor complexes.