Skip to main content
. 2009 Sep 29;122(20):3749–3758. doi: 10.1242/jcs.050625

Fig. 2.

Fig. 2.

RAB-D1 [N121I] inhibits secretory traffic between the ER and Golgi. (A) Confocal images of tobacco leaf epidermal cells expressing the ER luminal marker GFP-HDEL or the secreted GFP marker secGFP either alone or together with wild-type or the N121I mutant forms of RAB-D1. (B) Quantification of the effect of RAB-D1 and the indicated mutants on the intracellular accumulation of secGFP (green bars). The fluorescence signal from the ER-lumenal marker GFP-HDEL (blue bar) was set to 1 and that for secGFP alone to 0. Error bars represent standard deviation of each sample. (C,D) Use of ratiometric fluorescent polyproteins to localise secreted and Golgi markers in the presence of RAB-D1 [N121I] and RAB-D2a [N121I]. (C) nlsR-2A-secG expresses secGFP (green) and a nuclear-targeted RFP (red) in fixed stoichiometry as a polyprotein linked by the self-cleaving 2A polypeptide (Samalova et al., 2006). Transfected cells are marked by red nuclei but do not accumulate GFP, which is secreted to the cell wall (top). In the presence of RAB-D1 [N121I] (bottom) or RAB-D2a [N121I] (centre), cells expressing similar quantities of the marker have similarly bright RFP signals in their nuclei, but now secGFP accumulates in a polygonal and planar ER network. (D) N-ST-R-2A-GH expresses the Golgi marker N-ST-RFP (red) in fixed stochiometry with the ER-marker GFP-HDEL (green), which indicates the relative expression level in each cell. In the presence of RAB-D1 [N121I] and RAB-D2a [N121I], the Golgi marker accumulates in the ER where it colocalises with GFP. In C and D, chlorophyll is blue. Scale bars:100 μm in A; 10 μm in C and D.