Figure 4.

Direct membrane contact between ER and LD. (A) Direct membrane contact between ER and LD could be observed in reconstructed tilt-series from high-pressure frozen, freeze-substituted (acetone containing 0.2% uranyl acetate, 2% osmium tetroxide and 1% H₂O) and Epon embedded HeLa cells (arrowheads). (B) Model of the reconstructed tomogram showing LDs (light blue), ER membranes (pink), MVB (blue) with internal vesicles (red), mitochondria (green) and the nuclear envelope (purple). While membrane contrast was sufficient to allow for efficient reconstruction of the tilt-series, LDs appeared extracted. er: endoplasmic reticulum, g: Golgi, ld: lipid droplet, m: mitochondria, MVB: multivesicular body, n: nucleus. Images courtesy of Dr. Rob Mesman.