Table S1. Dimensions of the ER–mitochondria interaction areas

Fixation method Tomogram Patch number Patch diameter Tether length
Dimensions of tethers in isolated liver mitochondria with attached vesicles
Frozen hydrated 1 1 180 nm 9 ± 2 nm
  2 1 80 nm 10 ± 1 nm
  2 2 100 nm 15 ± 2 nma
  3 1 70 nm 10 ± 3 nm
  3 2 100 nm 6 ± 2 nma
Chemical fixation 1 1 50 nm 9 ± 1 nm
Dimensions of tethers between smooth ER and OMM in liver
Freeze substitution 1 1 60 nm 14 ± 3 nm
  1 2 50 nm 10 ± 2 nma
  2 1 110 nm 16 ± 5 nm
Dimensions of tethers between rough ER and OMM in liver
Freeze substitution 1 1   21 ± 5 nm
  1 2   27 ± 9 nm
  2 1   26 ± 8 nm
  2 2   30 ± 9 nm
        Group Avg: 26 ± 8 nm
Dimensions of tethers between rough ER and OM in DT40 cells
Chemical fixation 1 1   19 ± 6 nm
  2 1   24 ± 6 nm
  3 1   27 ± 10 nm
        Group Avg: 23 ± 8 nm
aSignificant difference in mean between patches within tomogram. P < 0.01 by t-test.