The various organelles are in surprisingly close contact with each other in the cells. This is used for the exchange of substances and signals.
Hardly anyone noticed when Jean Vance discovered something fundamental about cell components 30 years ago. At first she even doubted her results, because the path to her discovery had been full of obstacles. Vance worked alone as a cell biologist in a newly established laboratory at the University of Alberta in Edmonton, Canada. In one of her experiments, she experimented with rat livers and isolated pure mitochondria from them - at least that's what she thought - the cell organelles that provide a cell with usable energy and therefore resemble tiny power plants. However, tests revealed that her sample contained something else that wasn't supposed to be in there. "I thought I had made a big mistake," the researcher recalls.
After additional cleaning steps, the cell biologist found that various structures from the inside of the cell were sticking to the mitochondria – like chewing gum on the sole of a shoe. These were components of the endoplasmic reticulum (ER), another cell organelle that resembles a branched channel system and is used to produce proteins and fats. Other biologists had already observed that parts of the ER sometimes get stuck on mitochondria, but interpreted this as an effect that was artificially created by the sample treatment. Vance, on the other hand, recognized that the organelles are not glued together for no reason – and this could be the solution to a great mystery of cell biology…