Figure 7.

Interaction of N-type calcium channels but not sodium channels with SNARE proteins. Rat brain membranes (P2L) were labeled with [³H]STX (A) and ¹²⁵I-ωGVIA (B), were extracted with Triton X-100, and were incubated with antibodies against synaptotagmin (mAb 1D12), VAMP 2, syntaxin 1, SNAP-25, and non-immune IgG. The radioactivity recovered in immune complexes was determined by scintillation counting (mean ± SD, n = 6) and was expressed as a percentage of total labeled channels. Nonspecific radioactivity detected by immunoprecipitation with control IgG was subtracted. (C) Sodium channels and N-type calcium channels were labeled with [³H]STX and ¹²⁵I-ωGVIA, respectively. Detergent extracts were incubated with an antibody against the sodium channel β1 subunit, an antibody that recognizes the α1A and α1B subunits of P/Q- and N-type calcium channels (B1Nt) or non-immune IgG. The radioactivity recovered in immune complexes was counted and expressed as described above (mean ± SD, n = 6). Some SD values were too small to be seen on graphs.