Western blot analysis of detergent-solubilized hippocampal slices (−) and intact hippocampal slices cross-linked with 4 mm DSP (DSP) for 45 min or 4% paraformaldehyde (PF) for 7, 15, 30, or 45 min before detergent solubilization (tube slices). Forty microliters of each hippocampal homogenate were loaded on a 10% polyacrylamide gel and fractionated by PAGE. Membranes were probed with anti-SNAP25 polyclonal (A) or anti-syntaxin monoclonal (B). Proteins were separated for different distances in A and B to separate the indicated complexes maximally. SNAP25- and syntaxin-containing protein complexes were identified. The molecular mass of the SNAP25- and syntaxin-containing bands were evaluated by simultaneously running molecular weight standards as described in Materials and Methods. The results are representative of four independent experiments.