For cell fractionation 100 mg tissue of transiently transformed tobacco leafs were homogenised in liquid nitrogen and the homogenate was extracted in 2 ml homogenization buffer (25 mM MOPS, 0.1 mM MgCl₂, 8 mM L-cysteine, 2.5 mM EDTA, 2× protease inhibitor mix (Roche), 250 mM sucrose; pH 7.8). The crude extract was cleared from debris by centrifugation (4000xg, 40 min, 4°C). The microsomal fraction was separated from the soluble fraction by ultracentrifugation (100,000xg, 30 min, 4°C). The pellet was washed three times in homogenization buffer supplemented with 0.05% Triton X-100 and resuspended in 50 μl SDS-PAGE sample buffer. The soluble fraction was mixed with SDS-PAGE sample (ratio: 21 v/v). For SDS-PAGE 18 μl of the soluble fraction and 10 μl of microsomal fraction were loaded. Western blot analysis and immunodetection were performed according to [61] using anti-GFP antibody (Roche, Switzerland) to detect GFP-AHK5, BRI1-GFP, ERS1-GFP and ARR4-GFP. An anti-mouse-AP conjugate (BioRad, UK) was used as secondary antibody.