Figure 5.

Transmission electron microscopy of GRASP55-depleted Golgi. (A and B) Representative TEM thin sections showing Golgi from control and GRASP55-depleted cells. Bar, 500 nm. (C) Quantitative representation of Golgi ribbon length in thin sections from control and GRASP55-depleted cells. The length of membrane profiles was estimated using the freehand line tool in ImageJ (n = 3, ≥20 profiles each, ±SEM). (D) Golgi stack lengths from a representative experiment were divided into size class bins and presented in histogram format to illustrate the distinct distributions of stack lengths in the presence (black diamonds) and absence (gray squares) of GRASP55. Note that despite the variation evident in the histogram, the error in panel C is small because the average stack length was consistent across multiple experiments. (E) Masks were drawn over Golgi membranes taken from a contiguous stack of TEM serial sections (representative sections are shown in insets) and reassembled into a 3D volume. The full 3D representations are provided as supplemental movies (see Supplemental Figures S6 and S7).