A model of the Golgi ministack. (A) The composite image of side-averaged Golgi proteins demonstrating the organization of the Golgi ministack. Selected side-average images of Golgi proteins were further reflection-averaged (Fig. S3) and merged. Scale bar, 200 nm. (B) A schematic diagram of an average Golgi ministack. The diagram was constructed roughly to the scale according to our side-average data and the composite image in A. The unit in the x and y axis is nm. 0 nm in the x and y axis corresponds to the Golgi axis and the fluorescence center of GM130 (LQ = 0), respectively. The maximal lateral size of the stacked cisternae is 700 nm, corresponding to that of giantin. The axial size of the ministack is 274 nm. The axial positions of ERES/ERGIC, cis, medial, trans, and TGN regions were calculated by multiplying their LQ intervals, (−∞, −0.25), [−0.25, 0.25), [0.25, 0.75), [0.75, 1.25], and [1.25, ∞), respectively, with one unit of LQ (the axial distance from GM130 to GalT-mCherry), which is 274 nm.