Figure 6.

Resident ER membrane proteins tagged with GFP on their cytoplasmic domains can induce OSER formation. (a) Illustration of constructs and their orientations. The differently shaded rectangles represent the distinct single TMD resident ER proteins and the barrel structure represents GFP. (b) Representative confocal micrographs of cells expressing the GFP chimeras. (c) To visualize the mobility of the GFP chimeras within whorls a small region of interest (yellow outlined square) was photobleached and monitored for recovery (c). To compare the mobility of GFP chimeras between branching reticular ER (d) and exchange into and out of whorls (e), regions of interest (yellow outlined squares) of identical size were photobleached and monitored for recovery in cells expressing GFP-Sec61γ. Bars, 5 μm. (f and g) Fluorescence intensity recovery plots compare the rates of recovery of GFP-Sec61γ within the whorl (black diamonds), branching reticular ER (open red circle), and into the whole whorl (open green squares) for the image series in c, d, and e, respectively.