The cell nucleus is an organelle, in which the DNA of an organism is protected and duplicated. The nucleus of this organ-like structure in the cell plasma is surrounded by an outer and an inner nuclear envelope, which is penetrated by openings – so-called nuclear pores. The outer nuclear envelope is also connected to the endoplasmic reticulum (ER), another organelle. Up until now, scientists assumed that only the ER and the outer nuclear envelope were involved in the cell’s lipid metabolism and that the inner envelope obtained its lipids exclusively through the nuclear pores. A team of researchers from Max F. Perutz Laboratories, a subsidiary of the University of Vienna and Medical University of Vienna, has discovered that the inner membrane exhibits a unique type of metabolic activity.