Figure 1. FLAP homodimer in PMN and Sf9 cells.

(A) Immunoblot analysis of human PMN membrane proteins with the FLAP antiserum anti-H5. Membranes from 15×10⁶ PMN equivalent were resuspended in HBSS and treated with the cross-linker sulpho-HSAB (20 μg/ml) for 15 min. The reaction was stopped with sample buffer and proteins were analysed by SDS/PAGE using a 5–20% gradient. (B) Immunoblot analysis of Sf9 cell membrane proteins with the FLAP antiserum anti-H4. Sf9 cells were infected for 3–4 days with a baculovirus containing FLAP. Sf9 cells were sonicated in HBSS and membranes from 5×10⁶ cell equivalents were resuspended in HBSS. Cross-linking and electrophoresis were performed as in (A). (C) Gel-strip 2D-electrophoresis of Sf9 cell membranes. The sample was prepared as in (B), treated with the cross-linker and processed as described in the Material and methods section. Proteins were separated first on a pH 3–10 gradient strip and then by 5–20% SDS/PAGE gradient. The membrane was blotted with the FLAP antiserum anti-H5. M-H, membrane treated with the cross-linker sulpho-HSAB; M, untreated membranes. Results shown are from one experiment and are representative of four different experiments.