Preparation of antisera specific to AtPEP12p or AtVAM3p. A, Antibodies raised against C- or N-terminal epitopes of AtPEP12p or against the cytoplasmic domain of AtVAM3p recognize bands of similar size (approximately 36 kD) following SDS-PAGE of Arabidopsis microsomal extracts. B, Affinity-purified antisera to each t-SNARE do not cross-react. Extracts from yeast cells expressing the cDNA for AtPEP12 (lanes 1, 3, and 5) or AtVAM3 (lanes 2, 4, and 6) were separated by SDS-PAGE, then probed with affinity-purified antisera to either C-terminal-specific AtPEP12p, N-terminal-specific AtPEP12p, or AtVAM3p. C, Expression of epitope-tagged t-SNAREs in transgenic Arabidopsis. Microsomal extracts from wild-type plants (lanes 1, 4, and 7), plants expressing T7-AtPEP12 (lanes 2, 5, and 8), and plants expressing T7-AtVAM3 (lanes 3, 6, and 9) were separated by SDS-PAGE, and then probed with T7 monoclonal antibodies or with affinity-purified antisera to either C-terminal-specific AtPEP12p or AtVAM3p.