The Subcellular Distribution of a Sar1-YFP Fusion Is Altered by the Expression of Golgi Markers.(A) and (B) Cytoplasm of a tobacco leaf epidermal cell expressing Sar1-YFP ([A]; scale bar = 5 μm) and cYFP ([B]; scale bar = 2 μm). The Subcellular Distribution of a Sar1-YFP Fusion Is Altered by the Expression of Golgi Markers.(A) and (B) Cytoplasm of a tobacco leaf epidermal cell expressing Sar1-YFP ([A]; scale bar = 5 μm) and cYFP ([B]; scale bar = 2 μm). Open and closed arrows indicate fluorescence accumulations visible in both Sar1-YFP and cYFP that surround organelles, visible in negative contrasts, that are similarly shaped and sized in both cells. White arrowheads point to bright punctate structures, and a bordered arrowhead points at a bright ring-like structure. These structures are observable in Sar1-YFP but not in cYFP-expressing cells.(C) Epidermal cell coexpressing ERD2-GFP and cytoplasmic YFP (cYFP). Note the absence of accumulation of the YFP fluorescence in punctate structures in the vicinity of individual Golgi bodies. Scale bar = 5 μm.(D) and (E) Coexpression of Sar1-YFP with the Golgi markers ERD2-GFP (D) and ST-GFP (E). In cells coexpressing ERD2-GFP and Sar1-YFP (D), the latter maintains a cytosolic pattern but also accumulates in punctate structures in the Golgi body vicinity (scale bar = 5 μm). Comparable to this, in cells coexpressing ST-GFP and Sar1-YFP, the latter is cytosolic but it is also distributed in punctate structures seemingly colocalizing with the Golgi bodies ([E]; scale bar = 5 μm). In addition, bright punctate structures ([D] and [E], white arrowheads) and ring-like structures ([D] and [E], bordered arrowhead) that do not colocalize with a Golgi marker are detectable.(F) and (G) Effect of Sar1[H74L]p on the distribution of Golgi markers. The fluorescence of ERD2-GFP (F) and ST-GFP (G) is located in the ER upon coexpression of the untagged Sar1p-GTP mutant (scale bar = 5 μm). Luis L.P. daSilva et al. Plant Cell 2004;16:1753-1771 ©2004 by American Society of Plant Biologists