Fig. 2. Expression of Syt IX in RBL cells. (A) Cell extracts (60 µg) derived from Cos-7 cells transfected with empty vector, T7-tagged Syt IX cDNA or Flag-tagged Syt IX cDNA were resolved by SDS-PAGE and subjected to immunoblotting with anti-N-Syt IX (1 µg/ml), anti-T7 or anti-Flag antibodies. (B) Cell extracts (60 µg) derived from Cos-7 cells transfected with empty vector or with Syt I, Syt II, Syt III, Syt V and Syt IX cDNAs were resolved by SDS-PAGE and subjected to immunoblotting with anti-N-Syt IX antibodies. (C) Cell extracts (80 µg) derived from RBL cells stably transfected with either empty vector (1), or with pcDNA3-Syt IX sense cDNA, RBL-Syt IX⁺ (2) or with pcDNA3-Syt IX antisense cDNA, RBL-Syt IX^– (3) were resolved by SDS-PAGE and subjected to immunoblotting with anti-N-Syt IX antibodies in the absence (1-3) or presence (4) of the immunizing peptide (250 ng/ml). (D) Cell extracts (80 µg) derived from RBL-Syt IX⁺ cells were resolved by SDS-PAGE and subjected to immunoblotting with anti-C2A-Syt IX antibodies (1 µg/ml). The cellular level of actin was determined to judge for equal loading. (E) Cell extracts (80 µg) derived from RBL cells stably transfected with pShooter Syt IX-GFP cDNA were resolved by SDS-PAGE and subjected to immunoblotting with anti-GFP, anti-C2A-Syt IX or anti-N-Syt IX as indicated.