Membrane contact sites promote lipid exchange Most membrane lipids are manufactured in the endoplasmic reticulum (ER). Different organelles and the plasma membrane (PM) have distinct phospholipid compositions. Chung et al. , working in mammalian cells, and Moser von Filseck et al. , working in yeast, both describe how a family of proteins is important in maintaining the balance of lipids within the cell. These special proteins accumulate at and tether contact sites between the ER and the PM and promote the exchange of specific phospholipids, which helps to maintain the PM's distinct identity. Science , this issue pp. 428 and 432

Phosphatidylserine transport by ORP/Osh proteins is driven by phosphatidylinositol 4-phosphate